The sixth season boasts some of the highest-rated episodes for the show so far, with a then-new series high set with "The Bakersfield Expedition", with 20 million viewers,[97] a first for the series, which along with NCIS, made CBS the first network to have two scripted series reach that large an audience in the same week since 2007. In the sixth season, the show became the highest rated and viewed scripted show in the 18–49 demographic, trailing only the live regular NBC Sunday Night Football coverage,[98][99] and was third in total viewers, trailing NCIS and Sunday Night Football.[100] Season seven of the series opened strong, continuing the success gained in season six, with the second episode of the premiere, "The Deception Verification", setting the new series high in viewers with 20.44 million.[101][102]

^ From the eighth season onward, episodes of each season initially aired on Monday nights, before later returning to the Thursday night slot for the rest of the season. The eighth and ninth seasons returned on the seventh episode,[126][127] the tenth and eleventh seasons on the sixth episode,[128][129] and the twelfth season on the second episode.[130]

In March 2017, CBS renewed the series for two additional seasons, bringing its total to twelve, and running through the 2018–19 television season.[3] On August 22, 2018, CBS and Warner Bros. Television officially announced that the twelfth season would be the series' last. This stems from Jim Parsons' decision to leave the series at the end of the season if the show were to have been renewed for a thirteenth season.[1][4][5] The series concluded with an hour-long finale consisting of two back-to-back episodes on May 16, 2019.[6][7] A retrospective, hosted by Johnny Galecki and Kaley Cuoco, aired at 9:30 P.M. ET/PT, the night of the finale, following the season two finale of Young Sheldon.[8]


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]
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.
Kevin Sussman as Stuart Bloom (recurring seasons 2–5, 7, starring seasons 6, 8–12):[54] A mild-mannered, under-confident owner of a comic book store. A competent artist, Stuart is a graduate of the prestigious Rhode Island School of Design, and though he is socially awkward he possesses slightly better social skills. Stuart implies he is in financial trouble and that the comic book store now also is his home. He is later invited to join the guys' group while Howard is in space. Stuart gets a new job caring for Howard's mother later. After Mrs. Wolowitz's death, Stuart continues to live in her home, along with Howard and Bernadette, until he finds a place of his own.
When Leonard receives a braggy Christmas letter from his brother, he feels bad about how little he and Penny have achieved in the past year. Leonard wonders if he and Penny should be thinking about the next step after two years of marriage, like buying a house or having a baby. Penny tells him she wants to do all those things someday, but she has a bunch of stuff she would like to do first.

As the theme of the show revolves around science, many distinguished and high-profile scientists have appeared as guest stars on the show. Famous astrophysicist and Nobel laureate George Smoot had a cameo appearance in the second season.[56] Theoretical physicist Brian Greene appeared in the fourth season, as well as astrophysicist, science populizer, and physics outreach specialist Neil deGrasse Tyson, who also appeared in the twelfth season.
"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."

Like the previous three seasons, the first five episodes aired on Mondays due to CBS' contractual rights to air the Thursday Night Football games. After Thursday Night Football ended, the series returned to a Thursday schedule starting on November 2, 2017. Filming for the eleventh season began on August 15, 2017; it was also announced with the taping report that the premiere for the eleventh season would be titled "The Proposal Proposal". Before the season premiered, five episodes were filmed from August 15 to September 19, 2017.[4]
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]
However, no legal action was required to end production of the other show: as soon as it became known that the show was unlicensed, the actors quit and the producers canceled it.[209] Dmitriy Tankovich (who plays Leonard's counterpart, "Seva") said in an interview, "I'm upset. At first, the actors were told all legal issues were resolved. We didn't know it wasn't the case, so when the creators of The Big Bang Theory started talking about the show, I was embarrassed. I can't understand why our people first do, and then think. I consider this to be the rock bottom of my career. And I don't want to take part in a stolen show".[210]
The first and second pilots of The Big Bang Theory were directed by James Burrows, who did not continue with the show. The reworked second pilot led to a 13-episode order by CBS on May 14, 2007.[10] Prior to its airing on CBS, the pilot episode was distributed on iTunes free of charge. The show premiered on September 24, 2007, and was picked up for a full 22-episode season on October 19, 2007.[11] The show is filmed in front of a live audience,[12] and is produced by Warner Bros. Television and Chuck Lorre Productions.[13] Production was halted on November 6, 2007, due to the Writers Guild of America strike. Nearly three months later, on February 4, 2008, the series was temporarily replaced by a short-lived sitcom, Welcome to The Captain. The series returned on March 17, 2008, in an earlier time slot[14] and ultimately only 17 episodes were produced for the first season.[15][16]
Howard dresses as Sheldon for Halloween at work, hurting Sheldon's feelings. When Howard does not apologize, Amy and Sheldon dress as Bernadette and Howard at Penny and Leonard's party, angering Bernadette. Sheldon and Bernadette later bond over their painful childhood memories. Leonard is upset that Penny does not seem to remember that their first kiss was on Halloween. Penny later admits she does remember, but does not like to think of their first kiss as an unromantic drunken hookup. She likes to imagine their first kiss was one they shared on Leonard's birthday, which pleases him.
Cosmologist Stephen Hawking made a short guest appearance in the fifth-season episode;[57] in the eighth season, Hawking video conferences with Sheldon and Leonard, and makes another appearance in the 200th episode. In the fifth and sixth seasons, NASA astronaut Michael J. Massimino played himself multiple times in the role of Howard's fellow astronaut. Bill Nye appeared in the seventh and twelfth seasons.

Simon Helberg doesn't have any projects listed in development as of now, but he has had a burgeoning movie career. He was nominated for a Golden Globe for Florence Foster Jenkins and also appeared in Paint It Black. Maybe he's holding out hope for a spinoff for his Howard Wolowitz? When THR asked creator Chuck Lorre if he was gestating on ideas for any Big Bang character spinoffs, he coyly responded, "You can't help but gestate a little..."
^ From the eighth season onward, episodes of each season initially aired on Monday nights, before later returning to the Thursday night slot for the rest of the season. The eighth and ninth seasons returned on the seventh episode,[126][127] the tenth and eleventh seasons on the sixth episode,[128][129] and the twelfth season on the second episode.[130]
With Melissa Rauch saying goodbye to Bernadette Rostenkowski-Wolowitz after joining the show in season three and becoming a series regular in season four, she's already begun to carve out new gigs. Not only did her indie film Ode to Joy make its film festival debut this part April, but she has another film, Steven Soderbergh's The Laundromat co-starring none other than Meryl Streep, in post-production, due for a 2019 release. While wrapping up filming on TBBT, she landed her next TV gig, playing Shira, wife of Paul Scheer's Keith on Showtime's recent Wall Street comedy Black Sunday. With the show recently renewed for a second season to debut on the cable net in 2020, it's looking likely she'll be back with greater availability.

After learning Sheldon went behind their backs to work with the military again, Leonard and Howard say Sheldon is like Thomas Edison, taking credit for others' ideas, while they are more like Nikola Tesla. Leonard and Howard bring in Barry Kripke to help create a better idea than Sheldon's, but Kripke goes to the military himself, cutting all three of them out. Meanwhile, Bernadette fears Ruchi is trying to steal her projects at work while she is on maternity leave and enlists Raj to spy on her. Though he finds proof that Ruchi may be stealing from Bernadette, Raj tries to defend Ruchi like a boyfriend would, pointing out Bernadette's hypocrisy as she would most likely have stolen from other people's projects as well. Ruchi is not happy about this and promptly dumps Raj.


“The Big Bang Theory” premiered on Sept. 24, 2007, and for most of its run, was primetime’s most-watched comedy series. It remains one of the most successful sitcoms in TV history — and the longest-running multi-cam comedy of all time (recently surpassing “Cheers”). It has generated an estimated $1 billion and counting in syndication. The show has received 52 Emmy Award nominations and 10 wins, seven Golden Globe nominations, and the spinoff prequel, “Young Sheldon.”
^ "Editor's Note: With final Monday ratings in, The Big Bang Theory has now reached a new series high in viewers (16.32m) and was the night's top program in adults 18-49 (5.9/15), up a tenth from this morning. -- "Two and a Half Men" Soars to Its Best Adult 18-49 Rating in Three Years". CBS. March 9, 2010. Archived from the original on January 8, 2014. Retrieved January 5, 2013.
“The Big Bang Theory” premiered on Sept. 24, 2007, and for most of its run, was primetime’s most-watched comedy series. It remains one of the most successful sitcoms in TV history — and the longest-running multi-cam comedy of all time (recently surpassing “Cheers”). It has generated an estimated $1 billion and counting in syndication. The show has received 52 Emmy Award nominations and 10 wins, seven Golden Globe nominations, and the spinoff prequel, “Young Sheldon.”
By season seven, Galecki, Parsons, and Cuoco were also receiving 0.25% of the series' back-end money. Before production began on the eighth season, the three plus Helberg and Nayyar, looked to renegotiate new contracts, with Galecki, Parsons, and Cuoco seeking around $1 million per episode, as well as more back-end money.[36] Contracts were signed in the beginning of August 2014, giving the three principal actors an estimated $1 million per episode for three years, with the possibility to extend for a fourth year. The deals also include larger pieces of the show, signing bonuses, production deals, and advances towards the back-end.[37] Helberg and Nayyar were also able to renegotiate their contracts, giving them a per-episode pay in the "mid-six-figure range", up from around $100,000 per episode they each received in years prior. The duo, who were looking to have salary parity with Parsons, Galecki, and Cuoco, signed their contracts after the studio and producers threatened to write the characters out of the series if a deal could not be reached before the start of production on season eight.[38] By season 10, Helberg and Nayyar reached the $1 million per episode parity with Parsons, Galecki, and Cuoco, due to a clause in their deals signed in 2014.[39] 
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