See the Big Bang Theory cast at the start of the show vs the end

Sheldon Cooper was Jim Parsons’ debut acting role and one that saw him named as the highest-paid television actor of 2015. 

Since first appearing on screen in 2007, the actor has gone on to earn four Primetime Emmy Awards and a Golden Globe. His most recent project saw him play Warren in The Leader, a true-crime thriller based on the Heaven’s Gate cult. 

Johnny Galecki played Sheldon’s lovable roommate and fellow scientist at CAL-Tech, Leonard Hofstadter. The series saw us rooting for his and the ‘girl next door’ Penny’s romance throughout the series. 

Following the series’ end in 2019, he has chosen to step away from the limelight to focus on his family, with two young children and a wife.  

Known best for his failed pickup lines and shouting ‘Ma!’ across the house to his mother, only Simon Helberg could play an overgrown child who still lives in his mother’s house and who you can’t help but love. 

Since playing Howard Wolowitz on The Big Bang Theory, his career has grown from strength to strength. Simon was nominated for a Golden Globe for his role opposite Meryl Streep and Hugh Grant in Florence Foster Jenkins and, most recently, he appeared on The Audacity as Martin Phister. 

Kunal Nayyar plays the series’ sweetest character, Raj Koothrappali. And while he’s still best known for his role on The Big Bang Theory, other projects have included voice acting gigs on Ice Age and Trolls, as well as his role as Sandeep Singh in Criminal: UK, which earned the star a BAFTA nomination.   

Kunal has also authored a book, Yes, My Accent Is Real, and even pays off medical debt for struggling families. I suppose this star is just as sweet off-screen. 

After starting her career as a child star in Quicksand: No Escape, Kaley Cuoco was cast as female lead Penny, the series’ ‘girl next door’who is more often than not known as ‘Knock knock knock Penny’ when Sheldon Cooper wants her attention. She plays Leonard’s love interest throughout the series, and (spoiler!) the pair eventually get married in Las Vegas in season 10. 

But while her character plays a struggling actor who works at The Cheesecake Factory to get by, in real life Kaley has had far more success. In fact, she recently produced and starred in The Flight Attendant, earning Emmy and Golden Globe nominations. 

Melissa Rauch joined The Big Bang Theory cast in 2009 for her debut acting role as Bernadette Rostenkowski. Her character is high-pitched and takes no prisoners, especially with Howard, whom she develops a romantic relationship with and eventually marries in season five. Her role in the series saw her nominated for the Critics’ Choice Television Award’s Best Supporting Actor in 2013. 

Since playing Bernadette, she’s had a successful acting career, landing voice acting roles in Sofia the First, Jake and the Never Land Pirates and later appearing in the 2023 Night Court series. 

Mayim Bialik joined the sitcom’s cast in 2010 as Dr Amy Farrah Fowler, a neuroscientist and Sheldon’s love interest, with the pair eventually getting married by the season 11 finale.  

Mega fans of the sitcom might already know that, just like her fictional character Amy, Mayim also has a Ph.D. in neuroscience from the University of California, Los Angeles. 

After filming wrapped for The Big Bang Theory, the star had a stint as a Jeopardy! host between 2021 and 2023 and returned to comedy acting in 2021 as Kat in Call Me Kat. In 2021, she started a podcast with her boyfriend Jonathan Cohen, Mayim Bialik’s Breakdown, where they discuss mental health and science.