Warner Bros. Television controls the online rights for the show.[159][160] Full episodes are available at tv.com, while short clips and recently aired full episodes are available on cbs.com.[161] In Canada, recent episode(s) and pictures are available on CTV.ca.[162] Additionally in Canada, the first six seasons are available for streaming on Bell Media's CraveTV.[163] After the show has aired in New Zealand the shows are available in full online at TVNZ's on demand web service.
Leonard and Sheldon are brilliant physicists—geniuses in the laboratory but socially challenged everywhere else. Enter beautiful, street-smart neighbor Penny, who aims to teach them a thing or two about life. Despite their on-again, off-again relationship in the past, Leonard and Penny have finally gotten married. Even Sheldon has found a female companion, entering into a "relationship agreement" with neurobiologist Amy Farrah Fowler, and he recently took their relationship to the next level by marrying her after a long courtship. In their free time, Leonard and Sheldon enjoy fantasy role-playing games with their ever-expanding universe of friends, including fellow scientists Koothrappali, Wolowitz, and Wolowitz’s adorable microbiologist wife, Bernadette, who is adjusting to life with their two children.
Leonard and Sheldon are brilliant physicists—geniuses in the laboratory but socially challenged everywhere else. Enter beautiful, street-smart neighbor Penny, who aims to teach them a thing or two about life. Despite their on-again, off-again relationship in the past, Leonard and Penny have finally gotten married. Even Sheldon has found a female companion, entering into a "relationship agreement" with neurobiologist Amy Farrah Fowler, and he recently took their relationship to the next level by marrying her after a long courtship. In their free time, Leonard and Sheldon enjoy fantasy role-playing games with their ever-expanding universe of friends, including fellow scientists Koothrappali, Wolowitz, and Wolowitz’s adorable microbiologist wife, Bernadette, who is adjusting to life with their two children.
Sheldon and Amy go on their honeymoon to New York City, starting with Legoland New York. Sheldon's insistence on scheduling their marital relations stresses Amy. He says he only does it to remind himself to be intimate with her. They compromise by letting him make a schedule without sharing it with her. Leonard and Penny discover Mr. Larry Fowler (Teller) in Sheldon and Amy's apartment hiding from his wife (Kathy Bates). Leonard notices parallels in his own marriage, which offends Penny. Leonard apologizes, and Penny convinces Mrs. Fowler to give her husband a break. When Mrs. Fowler wants to hang out with her regularly, Penny scares Larry out of the building. Raj instigates a Twitter feud with Neil deGrasse Tyson but is scared off when confronted over the phone. Neil then calls Bill Nye to scare him, too.
And while the actor, 44, doesn't have any other gigs lined up just yet—his most recent stab at producing, CBS' Living Biblically, was canceled after 13 episodes in 2018—he's busy preparing for his biggest role yet: fatherhood. On May 3, 2019, he and girlfriend Alaina Meyer announced that they were expecting their first child together. "We are absolutely over the moon to announce that we will soon be welcoming a little one into this crazy and wonderful world," he wrote on social media, sharing the big news. "There truly is love out there for all. We hope ours is the ember of yours, as we feel yours is the ember of ours."
In scenes set at Howard's home, he interacts with his rarely-seen mother (voiced by Carol Ann Susi until her death) by shouting from room to room in the house. She similarly interacts with other characters in this manner.[85] She reflects the Jewish mother stereotype in some ways, such as being overly controlling of Howard's adult life and sometimes trying to make him feel guilty about causing her trouble. She is dependent on Howard, as she requires him to help her with her wig and makeup in the morning. Howard, in turn, is attached to his mother to the point where she still cuts his meat for him, takes him to the dentist, does his laundry and "grounds" him when he returns home after briefly moving out.[86] Until Howard's marriage to Bernadette in the fifth-season finale, Howard's former living situation led Leonard's psychiatrist mother to speculate that he may suffer from some type of pathology,[87] and Sheldon to refer to their relationship as Oedipal.[88] In season 8, Howard's mother dies in her sleep while in Florida, which devastates Howard and Stuart, who briefly lived with Mrs. Wolowitz.
The Big Bang Theory started off slowly in the ratings, failing to make the top 50 in its first season (ranking 68th), and ranking 40th in its second season. When the third season premiered on September 21, 2009, however, The Big Bang Theory ranked as CBS's highest-rated show of that evening in the adults 18–49 demographic (4.6/10) along with a then-series-high 12.83 million viewers.[94] After the first three seasons aired at different times on Monday nights, CBS moved the show to Thursdays at 8:00 ET for the 2010–2011 schedule, to be in direct competition with NBC's Comedy Block and Fox's American Idol (then the longest reigning leading primetime show on U.S. television from 2004 to 2011).[95] During its fourth season, it became television's highest rated comedy, just barely beating out eight-year champ Two and a Half Men. However, in the age 18–49 demographic (the show's target age range), it was the second highest rated comedy, behind ABC's Modern Family. The fifth season opened with viewing figures of over 14 million.[96]
Sheldon and Amy's wedding day arrives, with many friends and family attending, including Amy's domineering mother (Kathy Bates) and quiet father (Teller); Sheldon's mother Mary, brother George, and sister Missy, who is pregnant with her second child and separated from her husband; and Mark Hamill, who replaces Wil Wheaton as officiant as a favor to Howard who returned his lost dog. Sheldon cannot get his bow-tie to be symmetrical and conversations with Amy and his mother give him an epiphany about superasymmetry. Sheldon and Amy, along with Leonard, get caught up figuring out the math of the theory during the wedding ceremony, making Hamill take Star Wars questions to stall for time. Penny retrieves the couple, who then decide that they have the rest of their lives to make science together. Amy and Sheldon then express their vows. Amy recites a set of heartfelt vows, leaving Sheldon initially at a loss for words, before he reciprocates her loving words. They are pronounced as husband and wife.
The Big Bang Theory started off slowly in the ratings, failing to make the top 50 in its first season (ranking 68th), and ranking 40th in its second season. When the third season premiered on September 21, 2009, however, The Big Bang Theory ranked as CBS's highest-rated show of that evening in the adults 18–49 demographic (4.6/10) along with a then-series-high 12.83 million viewers.[94] After the first three seasons aired at different times on Monday nights, CBS moved the show to Thursdays at 8:00 ET for the 2010–2011 schedule, to be in direct competition with NBC's Comedy Block and Fox's American Idol (then the longest reigning leading primetime show on U.S. television from 2004 to 2011).[95] During its fourth season, it became television's highest rated comedy, just barely beating out eight-year champ Two and a Half Men. However, in the age 18–49 demographic (the show's target age range), it was the second highest rated comedy, behind ABC's Modern Family. The fifth season opened with viewing figures of over 14 million.[96]
Through the use of his vanity cards at the end of episodes, Lorre alleged that the program had been plagiarized by a show produced and aired in Belarus. Officially titled Теоретики (The Theorists), the show features "clones" of the main characters, a similar opening sequence, and what appears to be a very close Russian translation of the scripts.[207] Lorre expressed annoyance and described his inquiry with the Warner Bros. legal department about options. The television production company and station's close relationship with the Belarus government was cited as the reason that any attempt to claim copyright infringement would be in vain because the company copying the episodes is operated by the government.[208]
“I was there the moment when Leonard and Penny met. He said to me that their babies would be smart and beautiful. And now that they’re expecting, I have no doubt that that will be the case,” Sheldon says, accidentally revealing the baby news even before Penny’s parents know. “I apologize if I haven’t been the friend that you deserve. But I want you to know, in my way, I love you all.”
Laura Spencer as Emily Sweeney (recurring seasons 7–8, 10, starring season 9):[55] A dermatologist at Huntington Hospital. Emily went to Harvard and delights in the macabre and states that she likes her job because she can cut things with knives. Prior to meeting Raj, Emily was set up on a blind date with Howard. After finding Emily's online dating profile, Raj has Amy contact her as his wingman instead. Their relationship becomes exclusive, but Raj later breaks up with Emily when he becomes infatuated with the bartender Claire (Alessandra Torresani).
In scenes set at Howard's home, he interacts with his rarely-seen mother (voiced by Carol Ann Susi until her death) by shouting from room to room in the house. She similarly interacts with other characters in this manner.[85] She reflects the Jewish mother stereotype in some ways, such as being overly controlling of Howard's adult life and sometimes trying to make him feel guilty about causing her trouble. She is dependent on Howard, as she requires him to help her with her wig and makeup in the morning. Howard, in turn, is attached to his mother to the point where she still cuts his meat for him, takes him to the dentist, does his laundry and "grounds" him when he returns home after briefly moving out.[86] Until Howard's marriage to Bernadette in the fifth-season finale, Howard's former living situation led Leonard's psychiatrist mother to speculate that he may suffer from some type of pathology,[87] and Sheldon to refer to their relationship as Oedipal.[88] In season 8, Howard's mother dies in her sleep while in Florida, which devastates Howard and Stuart, who briefly lived with Mrs. Wolowitz.
In scenes set at Howard's home, he interacts with his rarely-seen mother (voiced by Carol Ann Susi until her death) by shouting from room to room in the house. She similarly interacts with other characters in this manner.[85] She reflects the Jewish mother stereotype in some ways, such as being overly controlling of Howard's adult life and sometimes trying to make him feel guilty about causing her trouble. She is dependent on Howard, as she requires him to help her with her wig and makeup in the morning. Howard, in turn, is attached to his mother to the point where she still cuts his meat for him, takes him to the dentist, does his laundry and "grounds" him when he returns home after briefly moving out.[86] Until Howard's marriage to Bernadette in the fifth-season finale, Howard's former living situation led Leonard's psychiatrist mother to speculate that he may suffer from some type of pathology,[87] and Sheldon to refer to their relationship as Oedipal.[88] In season 8, Howard's mother dies in her sleep while in Florida, which devastates Howard and Stuart, who briefly lived with Mrs. Wolowitz.

Live+7 data is currently available only through May 5, but the top dogs will likely see little change once the final numbers are in for the traditional September-May season. The top gainer in adults 18-49 was NBC’s “This Is Us” with an average lift of 1.8 ratings points. The number two spot was a tie between CBS’ “Big Bang Theory” and NBC’s “Manifest,” with both of those shows adding 1.5 ratings points on average. These numbers do not include “Big Bang Theory’s” series finale, however, which pulled in a 3.1 rating and 18 million viewers in Live+Same Day alone on May 16.
They are also fans of Star Wars, Battlestar Galactica, and Doctor Who. In the episode "The Ornithophobia Diffusion", when there is a delay in watching Star Wars on Blu-ray, Howard complains, "If we don't start soon, George Lucas is going to change it again" (referring to Lucas' controversial alterations to the films) and in "The Hot Troll Deviation", Katee Sackhoff of Battlestar Galactica appeared as Howard's fantasy dream girl. The characters have different tastes in franchises with Sheldon praising Firefly but disapproving of Leonard's enjoyment of Babylon 5.[76][n 1] With regard to fantasy, the four make frequent references to The Lord of the Rings and Harry Potter novels and movies. Additionally, Howard can speak Sindarin, one of the two Elvish languages from The Lord of the Rings.
Amy and Howard begin collaborating on a neuroprosthetics project, upsetting Sheldon and Raj, who feel they are not spending as much time with them. When they seek solace with an annoyed Bernadette, she exploits the situation to trick Sheldon into doing Howard's chores. Penny successfully employs the approaches recommended in one of Bernadette's parenting books to deal with Sheldon, but Leonard believes she is coddling Sheldon too much. Sheldon and Raj resolve the issue of missing their significant others by spending time together. 

Wil Wheaton brings William Shatner on his Professor Proton show to meet Sheldon, who gets so excited that he vomits on Shatner. Going to Wil to apologize, he finds Wil hosts a Dungeons & Dragons group with his celebrity friends including Shatner. Finding out Stuart is in the group and never told them, the guys make Stuart panic and quit. Wil secretly invites Leonard who discovers that the group also includes Shatner, Kevin Smith, Joe Manganiello and Kareem Abdul-Jabbar. Leonard tells Penny, who tells Amy and Bernadette, all three women having a crush on Manganiello. Because of that indiscretion, Wil kicks out Leonard and admonishes the guys for using him for his connections, and says that one of the worst things about being a celebrity is not knowing whether someone will like him for himself. To apologize, the guys invite Wil to play D&D with them at Leonard’s apartment, but Wil, secretly in the middle of a game with Penny, Amy and Bernadette and the group, politely turns them down, before allowing the girls to send them a photo of the events as payback.
Sheldon and Amy go on their honeymoon to New York City, starting with Legoland New York. Sheldon's insistence on scheduling their marital relations stresses Amy. He says he only does it to remind himself to be intimate with her. They compromise by letting him make a schedule without sharing it with her. Leonard and Penny discover Mr. Larry Fowler (Teller) in Sheldon and Amy's apartment hiding from his wife (Kathy Bates). Leonard notices parallels in his own marriage, which offends Penny. Leonard apologizes, and Penny convinces Mrs. Fowler to give her husband a break. When Mrs. Fowler wants to hang out with her regularly, Penny scares Larry out of the building. Raj instigates a Twitter feud with Neil deGrasse Tyson but is scared off when confronted over the phone. Neil then calls Bill Nye to scare him, too.
Live+7 data is currently available only through May 5, but the top dogs will likely see little change once the final numbers are in for the traditional September-May season. The top gainer in adults 18-49 was NBC’s “This Is Us” with an average lift of 1.8 ratings points. The number two spot was a tie between CBS’ “Big Bang Theory” and NBC’s “Manifest,” with both of those shows adding 1.5 ratings points on average. These numbers do not include “Big Bang Theory’s” series finale, however, which pulled in a 3.1 rating and 18 million viewers in Live+Same Day alone on May 16.

"Every heart expanding adventure begins with a single step. This was mine for @bigbangtheory_cbs," Rauch wrote. "My first episode. Or my first 'step-isode' - if you will. The second pic is shortly after I joined the cast (I couldn’t believe I had my very own dressing room)! The friendships and memories that would build from these moments simply overwhelm me."


Sheldon and Amy go on their honeymoon to New York City, starting with Legoland New York. Sheldon's insistence on scheduling their marital relations stresses Amy. He says he only does it to remind himself to be intimate with her. They compromise by letting him make a schedule without sharing it with her. Leonard and Penny discover Mr. Larry Fowler (Teller) in Sheldon and Amy's apartment hiding from his wife (Kathy Bates). Leonard notices parallels in his own marriage, which offends Penny. Leonard apologizes, and Penny convinces Mrs. Fowler to give her husband a break. When Mrs. Fowler wants to hang out with her regularly, Penny scares Larry out of the building. Raj instigates a Twitter feud with Neil deGrasse Tyson but is scared off when confronted over the phone. Neil then calls Bill Nye to scare him, too.
Simon Helberg as Howard Wolowitz:[45] An aerospace engineer who got his Masters at MIT. Howard is Jewish and lived with his mother, Debbie (Carol Ann Susi). Unlike Sheldon, Leonard, Raj, Bernadette and Amy, Howard does not hold a doctorate. He goes into space, training as an astronaut and serving as a payload specialist. Howard initially fancies himself as a womanizer, but he later starts dating Bernadette, and they get engaged and married. Howard also has a tendency to waste money on toys and argues with Bernadette because of his oddly low income as an engineer and her high income as a pharmaceutical biochemist.

In May 2010, it was reported that the show had been picked up for syndication, mainly among Fox's owned and operated stations and other local stations, with Warner Bros. Television's sister cable network TBS holding the show's cable syndication rights. Broadcast of old shows began airing in September 2011. TBS now airs the series in primetime on Tuesdays, Wednesdays, and Thursdays, with evening broadcasts on Saturdays (TBS's former local sister station in Atlanta also holds local weeknight rights to the series).[157] Although details of the syndication deal have not been revealed, it was reported the deal "set a record price for a cable off-network sitcom purchase".[158] CTV holds national broadcast syndication rights in Canada, while sister cable network The Comedy Network holds cable rights.
Sheldon cannot find the perfect wedding date and begins talking in his sleep, adopting the persona of a laid-back person who goes with the flow. Amy and Penny believe that his subconscious mind is trying to tell him to be more relaxed; his attempt to be so while wearing flip-flops ends in disaster. He decides to leave all the wedding planning to Amy while he wears a Star Trek uniform underneath his tuxedo. Meanwhile, Raj and Stuart both become interested in Bernadette's new coworker Ruchi. While she likes them both as friends, she does not want a relationship with anyone.
While Jim Parsons was the one who'd had enough with The Big Bang Theory, opting not to renew his contract to play socially awkward theoretical physicist Sheldon Cooper and bringing about the demise of the show in the process, he won't be escaping the show's orbit entirely. He's still attached as both executive producer and narrator of prequel series Young Sheldon, returning for a third season on CBS this fall. "There was no factor; there was no situation that I was like, 'Well, I've had enough of that.' No. There was nothing like that. It was just…when you know, you know," he explained to The Hollywood Reporter in mid-May. 
^ Jump up to: a b Kondolojy, Amanda (October 12, 2014). "'Gotham' Has Biggest Adults 18–49 Ratings Increase; 'Gotham' & 'Red Band Society' Top Percentage Gains & 'How To Get Away With Murder' Tops Viewer Gains in Live +7 Ratings for Week Ending September 28". TV by the Numbers. Archived from the original on October 16, 2014. Retrieved October 13, 2014.

Johnny Galecki as Leonard Hofstadter:[42] An experimental physicist with an IQ of 173, who received his PhD when he was 24 years old. Leonard is a nerd who loves video games, comic books, and Dungeons & Dragons. Leonard is the straight man of the series, in which he shares an apartment in Pasadena, CA, with Sheldon. Leonard is smitten with his new neighbor Penny when they first meet, and they eventually marry.
Sheldon's childhood friend from Texas, Tam, is visiting the university with his son. Sheldon does not want to see him and the others wonder why Sheldon has never mentioned Tam. Tam is unaware Sheldon is angry with him, thinking they just naturally drifted apart. Sheldon's brother George does not know the reason either. Sheldon eventually reveals Tam promised he would move to California with Sheldon, but then got a girlfriend and stayed with her, leaving Sheldon feeling abandoned. Tam and Sheldon make up and Sheldon has Leonard take Tam to the airport. Meanwhile, Penny and Bernadette want to get to know Anu, impressed by her connections in the hotel industry. They tell her embarrassing things about Raj and wonder if they can go out with her again after Raj confronts them.
In November 2016, it was reported that CBS was in negotiations to create a spin-off of The Big Bang Theory centered on Sheldon as a young boy. The prequel series, described as "a Malcolm in the Middle-esque single-camera family comedy" would be executive-produced by Lorre and Molaro, with Prady expected to be involved in some capacity, and intended to air in the 2017–18 season alongside The Big Bang Theory.[211][212] The initial idea for the series came from Parsons, who passed it along to The Big Bang Theory producers.[213] In early March 2017, Iain Armitage was cast as the younger Sheldon, as well as Zoe Perry as his mother, Mary Cooper. Perry is the real-life daughter of Laurie Metcalf, who portrays Mary Cooper on The Big Bang Theory.[213]

When Penny tells Leonard he needs to be more assertive in making decisions for himself, he starts standing up to Sheldon over small things. His confidence makes him want to demand the university support his idea for a plasma physics project. He threatens to quit if the university refuses, alarming both Sheldon and Penny, who consider this to be a risky career move. Sheldon is conflicted on whether or not he is being selfish over Leonard's decision, but Amy suggests that the fact that he is worried over Leonard's motivation proves that he does care about him, which he acknowledges. President Seibert refuses the project, but in order not to lose Leonard, gives him co-leadership over a photon entanglement project, leaving Leonard proud of himself and Penny impressed. Meanwhile, Raj shows Anu his lab, and suggests one possible answer for something he's seen in space might be alien life. When someone mentions this at his observatory presentation, the scientific community starts mocking him as a conspiracy theorist. Raj points out scientists should consider all possibilities when seeking the truth, though this causes people to think he believes in the Loch Ness Monster.
The show made its United Kingdom debut on Channel 4 on February 14, 2008. The show was also shown as a 'first-look' on Channel 4's digital offshoot E4 prior to the main channel's airing. While the show's ratings were not deemed strong enough for the main channel, they were considered the opposite for E4. For each following season, all episodes were shown first-run on E4, with episodes only aired on the main channel in a repeat capacity, usually on a weekend morning. From the third season, the show aired in two parts, being split so that it could air new episodes for longer throughout the year. This was due to rising ratings. The first part began airing on December 17, 2009, at 9:00 p.m. while the second part, containing the remaining eleven episodes, began airing in the same time period from May 6, 2010. The first half of the fourth season began airing on November 4, 2010, at 9:00 p.m., drawing 877,000 viewers, with a further 256,000 watching on the E4+1 hour service. This gave the show an overall total of 1.13 million viewers, making it E4's most-watched programme for that week. The increased ratings continued over subsequent weeks.[144]
Kunal Nayyar as Rajesh Koothrappali:[46] A particle astrophysicist originally from New Delhi, India. Raj is initially unable to talk to women unless he drinks alcohol. Raj also has very feminine tastes and often takes on a stereotypical female role in his friendship with Howard as well as in the group of four men. Raj later dates Lucy (Kate Micucci), who also suffers from social anxiety, but it eventually ends; he later speaks to Penny without alcohol and thus overcomes his selective mutism. He begins dating Emily and their relationship later becomes exclusive. Raj also has a Yorkshire Terrier named Cinnamon.
Sheldon needs half a billion dollars to prove his latest concept of string theory, which the University cannot afford to fund. Crowdfunding and selling some of his most valuable comic books to Stuart give him a small start. When Raj mentions gambling in Las Vegas, Sheldon goes there but is caught calculating odds by security before he can make any bets. Meanwhile, Amy takes Penny and Bernadette shopping for her wedding dress. She loves an old-fashioned one that the other girls admit that they find ugly, though Penny assures Amy she can make her own decisions about her wedding. Sheldon, however, comes home and sees Amy in the dress and loves how she looks.

Two physicists from Chicago, Dr. Campbell and Dr. Pemberton, accidentally prove Sheldon and Amy's super-asymmetry theory. This puts them on track for a Nobel Prize, but Leonard points out they tend to go to the experimental scientists who prove a concept instead of theorists like Sheldon who come up with it. Meeting with them, they tell Sheldon they are willing to share the Prize but only three names can be on the submission, and they want to cut Amy out. Amy does not want to prevent Sheldon's lifelong dream, but he goes to President Seibert who agrees to fight for Amy on their behalf. Meanwhile, Bernadette's drug has been approved and she wants to promote Penny to lead the marketing team. Penny resists, knowing Bernadette's attitude at work and doubting her own inexperience to take the responsibility, but Bernadette uses reverse-psychology to get Penny to take the job. Penny mirrors Bernadette's commanding style to get the other employees in line, impressing Bernadette.
Keith Carradine has appeared in three episode as Penny's father, Wyatt, first in Season 4. Katey Sagal, who played the on-screen mother of Kaley Cuoco's character in the 2002-2005 sitcom 8 Simple Rules, has appeared as Penny's mother in one episode of The Big Bang Theory. Jack McBrayer has appeared in one episode of The Big Bang Theory as Penny's brother, Randall.

Although earlier this season Penny (Kaley Cuocuo) told her husband Leonard (Johnny Galecki) that she never wanted kids, part two of the finale reveals that she is pregnant. But when Sheldon dismisses her announcement, Leonard angrily says “to hell with” his Nobel Prize. When his friends threaten to leave at his poor treatment of them, Sheldon takes time to self reflect.
After the strike ended, the show was picked up for a second season, airing in the 2008–2009 season, premiering in the same time slot on September 22, 2008.[17] With increasing ratings, the show received a two-year renewal through the 2010–11 season in 2009.[18][19] In 2011, the show was picked up for three more seasons.[20] In March 2014, the show was renewed again for three more years through the 2016–17 season. This marked the second time the series gained a three-year renewal.[21] In March 2017, the series was renewed for two additional seasons, bringing its total to 12, and running through the 2018–19 television season.[22]

Amy and Howard begin collaborating on a neuroprosthetics project, upsetting Sheldon and Raj, who feel they are not spending as much time with them. When they seek solace with an annoyed Bernadette, she exploits the situation to trick Sheldon into doing Howard's chores. Penny successfully employs the approaches recommended in one of Bernadette's parenting books to deal with Sheldon, but Leonard believes she is coddling Sheldon too much. Sheldon and Raj resolve the issue of missing their significant others by spending time together.
Laura Spencer as Emily Sweeney (recurring seasons 7–8, 10, starring season 9):[55] A dermatologist at Huntington Hospital. Emily went to Harvard and delights in the macabre and states that she likes her job because she can cut things with knives. Prior to meeting Raj, Emily was set up on a blind date with Howard. After finding Emily's online dating profile, Raj has Amy contact her as his wingman instead. Their relationship becomes exclusive, but Raj later breaks up with Emily when he becomes infatuated with the bartender Claire (Alessandra Torresani).
Johnny Galecki as Leonard Hofstadter:[42] An experimental physicist with an IQ of 173, who received his PhD when he was 24 years old. Leonard is a nerd who loves video games, comic books, and Dungeons & Dragons. Leonard is the straight man of the series, in which he shares an apartment in Pasadena, CA, with Sheldon. Leonard is smitten with his new neighbor Penny when they first meet, and they eventually marry.
In 2010, Leonard, Howard, and Raj mined a lot of Bitcoin, now worth thousands of dollars, but left Sheldon out due to his fear of tax implications. Flashbacks are shown of how the Bitcoin ended up on an old laptop of Leonard's, which Penny gave to her old boyfriend Zack after she and Leonard broke up. In 2017, Leonard and Penny retrieve the computer from Zack, who first shows them a video of a drunken Penny apologizing for breaking up with Leonard. The Bitcoin is not found on the laptop. Sheldon had moved it to a flash drive on Leonard's keychain to teach the guys a lesson, but Leonard lost the keychain years ago. A final flashback to 2013 shows Stuart discovering the flash drive, which he decides to erase and sell for $10.

Amy and Howard begin collaborating on a neuroprosthetics project, upsetting Sheldon and Raj, who feel they are not spending as much time with them. When they seek solace with an annoyed Bernadette, she exploits the situation to trick Sheldon into doing Howard's chores. Penny successfully employs the approaches recommended in one of Bernadette's parenting books to deal with Sheldon, but Leonard believes she is coddling Sheldon too much. Sheldon and Raj resolve the issue of missing their significant others by spending time together.
^ Jump up to: a b Kondolojy, Amanda (October 12, 2014). "'Gotham' Has Biggest Adults 18–49 Ratings Increase; 'Gotham' & 'Red Band Society' Top Percentage Gains & 'How To Get Away With Murder' Tops Viewer Gains in Live +7 Ratings for Week Ending September 28". TV by the Numbers. Archived from the original on October 16, 2014. Retrieved October 13, 2014.
Science has also interfered with the characters' romantic lives. Leslie breaks up with Leonard when he sides with Sheldon in his support for string theory rather than loop quantum gravity.[70] When Leonard joins Sheldon, Raj, and Howard on a three-month Arctic research trip, it separates Leonard and Penny at a time when their relationship is budding. When Bernadette takes an interest in Leonard's work, it makes both Penny and Howard envious and results in Howard confronting Leonard, and Penny asking Sheldon to teach her physics.[71] Sheldon and Amy also briefly end their relationship after an argument over which of their fields is superior.[72]
Sheldon and Amy are surprised to find that Wil Wheaton's new Professor Proton show is actually very entertaining and that Wil had Howard on as a guest. On Howard's suggestion, Sheldon apologizes to Wil, mending their friendship, and tells him he wants to be on the show; but Wil asks for Amy. Sheldon tells her to do it, but she says she often doesn't do things to avoid upsetting him. Sheldon is horrified when he realises how selfish he has been, especially when he finds out that the men do the same for him. Sheldon encourages Amy to go on the show to inspire girls to pursue science while trying to control his obvious jealousy for her. Meanwhile, Leonard writes a book about a physicist that solves a murder, the protagonist Logan Dean is based on himself. Bernadette points out Logan's mean boss Illsa is similar to Penny, who thinks it is based on Bernadette, though Leonard does not correct her. However, Bernadette tells Penny the truth, upsetting her and making her mad at Leonard. After calling his mother for advice, Leonard learns that Illsa is actually like her; but abandons the book when he realizes he wrote romantic tension into the relationship between the characters.
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