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.
Kaley Cuoco's life after The Big Bang Theory is going to be animated. Cuoco has signed on to voice and executive produce DC Universe's new Harley Quinn series. She'll play the titular character in the new streaming series targeted toward mature audiences. In 2017, she got the rights to The Flight Attendant, a miniseries based on the book of the same name, which she was poised to star in. The Flight Attendant follows Cassandra Bowden, a flight attendant, who wakes up, hungover, in her hotel room with a dead body next to her. She goes about her day and heads back to New York. is she the killer? That's what she wonders. "This is the first time I have a project that I'm kind of nurturing from the beginning, so it's been a really interesting experience," she told PopSugar in March. "It's got a lot of aspects. It's very sexy. It's a really well-written book, which is why I wanted to option it. I'm ready to bring the character to life."
Simon Helberg as Howard Wolowitz: 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.
Johnny Galecki as Leonard Hofstadter: 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.
Sara Gilbert as Leslie Winkle (recurring season 1, starring season 2, guest seasons 3, 9): A physicist who works in the same lab as Leonard. In appearance, she is essentially Leonard's female counterpart and has conflicting scientific theories with Sheldon. Leslie has casual sex with Leonard and later Howard. Gilbert was promoted to a main cast member during the second season but resumed guest star status because producers could not come up with enough material for the character. Gilbert returned to The Big Bang Theory for its 200th episode.
^ "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.