Johnny Galecki
CHARACTER: Leonard Hofstadter
Prior to starring in The Big Bang Theory, Galecki actually started his career on CBS in the 1987 miniseries Murder Ordained. Big Bang premiered on the same network 20 years later and eventually made Galecki became one of the highest-paid actors on television, reportedly banking over $1 million per episode by series' end.
In November 2020, Galecki and his girlfriend Alaina Meyer—who share son Avery, 2—broke up after more than two years together.
Jim Parsons
CHARACTER: Sheldon Cooper
Parsons captured the hearts of viewers around the world for his portrayal of Sheldon Cooper, winning four Emmys and a Golden Globe in the process. In October 2018, Forbes announced that Parsons was the highest-paid TV actor in the world, earning just over $1 million per episode. Bazinga!
Following the end of TBBT, Parsons starred in The Boys in the Band (both the Tony Award-winning stage version and its 2020 film adaptation) and Ryan Murphy's Netflix series, Hollywood, earning another Emmy nomination. Since 2017, he has served as the narrator and the executive producer of the prequel spinoff, Young Sheldon.
Parsons has been married to Todd Spiewak for five years.
Kaley Cuoco
CHARACTER: Penny
Just over two years after the series finale of 8 Simple Rules, Kaley Cuoco landed the role of Penny on The Big Bang Theory. During the show' run, Cuoco won trophies from the Critics' Choice and Teen Choice Awards. In 2010, Cuoco revealed to CBS Watch that she and Galecki privately dated for two years before ending their relationship in 2009. The co-stars remain close friends, with Galecki posting a sweet birthday tribute to Cuoco in December 2021.
Cuoco has earned two Emmy nominations for The Flight Attendant, which she also executive-produces, and voices Harley Quinn in the beloved DC Comics character's eponymous animated series. She stars in the Peacock rom-com Meet Cute opposite Pete Davidson and is set to portray Doris Day in an upcoming limited series about the iconic performer.
Following her split from second husband Karl Cook in September 2021 after three years of marriage, Cuoco and her boyfriend Tom Pelphrey made their red carpet debut at the 2022 Emmy Awards.
"I took a lot of time to myself and spent the year kind of figuring myself out," Cuoco told E! News at the Meet Cute premiere. "That's why I'd never want actual time travel because it would really mess with the real time of what your life needs to be. And then, I met Tom, and everything changed."
Kunal Nayyar
CHARACTER: Raj Koothrappali
Nayyar rose to fame as astrophysicist Raj Koothrappali, becoming one of the highest-paid actors on TV, alongside Galecki and Parsons. Nayyar voiced the character Guy Diamond in the Trolls film franchise.
Nayyar has been married to Neha Kapur since 2011.
Simon Helberg
CHARACTER: Howard Wolowitz
Two months before the premiere of The Big Bang Theory, Helberg married actress Jocelyn Towne. In May 2012, the couple welcomed their first child together, a daughter named Adeinle. Two years later, the duo welcomed a son, Wilder.
Plus, Helberg has appeared in films such as Florence Foster Jenkins, Annette and Space Oddity, and lent his voice to Young Sheldon.
Melissa Rauch
CHARACTER: Bernadette Rostenkowski
Melissa Rauch joined the cast of The Big Bang Theory in 2009 during the show's third season, playing Bernadette Rostenkowski. Rauch appeared on episodes of True Blood and The Office over the years and will executive produce and star in the upcoming Night Court sequel series.
She's been married to writer Winston Rauch since 2007 and the couple have two children, Sadie, 4, and Brooks, 2.
Mayim Bialik
CHARACTER: Amy Farrah Fowler
Bialik became a household name for her starring role in Blossom, which aired from 1990 to 1995. In 2010, Bialik joined the cast of The Big Bang Theory on the show's season three finale, going onto earn four Emmy and one, as well as one win at the Critics Choice Television Awards.
Bialik has served as the host of Jeopardy!, sharing the duties with Ken Jennings, since August 2021, and stars in and executive produces the Fox sitcom Call Me Kat. She has two sons—Miles, 16, and Frederick, 14—with her ex-husband, Michael Stone.