Here’s a guide to the cast of The Big Bang Theory and the characters they play. Co-created by ‘King of Sitcoms’ Chuck Lorre, The Big Bang Theory enjoyed a record-breaking run on CBS, airing for a total of 12 seasons and 279 episodes before coming to an end with an emotional series finale in 2019. Chronicling the lives of a group of geeky guys living in Pasadena and the unlikely friendship they strike up with their beautiful waitress/wannabe actress neighbor, the beloved sitcom was a perennial hit over its 12 year run and racked up a ton of awards, including ten Primetime Emmys and a Golden Globe.

Being a celebration of all things nerdy, The Big Bang Theory attracted a whole host of guest stars from sci-fi icons and scientific geniuses to pop culture legends. Alongside regular guest star Wil Wheaton, the sitcom also boasted cameos from fellow Star Trek alumni William Shatner, LeVar Burton and George Takei and Star Wars actors Mark Hamill and Carrie Fisher, plus appearances from physicist Stephen Hawking and Marvel Comics pioneer Stan Lee.

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The heart and soul of the show, of course, was its main cast. Read on for a who’s who guide to The Big Bang Theory’s cast and their characters.

The Big Bang Theory cast eating dinner at home

Johnny Galecki – Leonard Hofstadter

Johnny Galecki of Roseanne fame plays Leonard Hofstadter, an experimental physicist employed at Caltech who develops a major crush on his new neighbor Penny. Their eventual on-off relationship is a focus of many a The Big Bang Theory storyline.

Jim Parsons – Sheldon Cooper

Dr. Sheldon Cooper is a brilliant but socially awkward theoretical physicist who is Leonard’s roommate and colleague at Caltech in The Big Bang Theory. He’s played by Jim Parsons who won four Emmys for his performance. Sheldon Cooper is also the focus of spinoff show Young Sheldon.

Kaley Cuoco – Penny

Played by Kaley Cuoco (8 Simple Rules), Penny hails from Nebraska and moves to Pasadena in hopes of becoming an actress. Outgoing and decidedly non-nerdy, Penny is the polar opposite of Leonard and Sheldon but soon becomes one of their inner circle.

Simon Helberg – Howard Wolowitz

Leonard and Sheldon’s colleague and friend Howard Wolowitz (Simon Helberg, Florence Foster Jenkins) is an engineer that lives with his overbearing mother for much of the show. He fancies himself a ladies’ man but is anything but until he meets future wife Bernadette.

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Kunal Nayyar – Raj Koothrappali

British-Indian actor Kunal Nayyar (Sanjay And Craig) plays Raj Koothrappali on The Big Bang Theory, a pathologically shy astrophysicist that comes from a wealthy New Delhi family. He’s best pals with Howard and their friendship has been hailed as one of TV’s best bromances.

Melissa Rauch – Bernadette Rostenkowski-Wolowitz

Introduced in The Big Bang Theory’s third season, Bernadette Rostenkowski-Wolowitz is played by Melissa Rauch (The Bronze). The squeaky-voiced microbiologist begins dating Howard and the pair later tie the knot in the sitcom’s season 5 finale.

Mayim Bialik – Amy Farrah Fowler

Like Rauch, Blossom star Mayim Bialik joined The Big Bang Theory cast in season 3. Bialik plays Amy Farrah Fowler, a frumpy neurobiologist who is Sheldon Cooper’s main love interest and Penny and Bernadette’s best friend.

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