From Kaley Cuoco and Jim Parsons to Mayim Bialik and more

    We love rewatching episodes of The Big Bang Theory. The popular sitcom, which debuted in 2007, follows a group of geeks, including a NASA engineer, an astrophysicist and two physicists, and their lives both in and out of the lab.

    MORE: All we know about Kaley Cuoco's new role that made her move away from friends and family

    The Emmy award-winning series made household names out of its stars, but have you ever wondered how they got their start in TV? Keep reading to find out more about the incredible cast and their first on-screen roles...

    WATCH: Are you a fan of The Flight Attendant? 

    Johnny Galecki as Leonard Hofstadter 

    Leonard is the glue that holds the gang together and is played by actor Johnny Galecki. Johnny landed his first acting gig aged 7 when he was cast in CBS miniseries Murder Ordained. As a kid, he also starred in  and the series  and 

    Johnny Galecki plays Leonard

    MORE: See inside The Big Bang Theory star Kunal Nayyar's beautiful LA home

    MORE: See the Big Bang Theory cast and their real-life families

    Jim Parsons as Sheldon Cooper 

    Jim Parsons was born and raised in Texas, just like his character, the awkward but lovable Sheldon Cooper. He relocated to New York in his early twenties to pursue a career in acting and secured a few minor roles before landing the part on the sitcom. One of his earliest roles that caught the attention of viewers was in an advert for Quiznos.

    Jim Parsons played minor roles before landing 

    Kaley Cuoco as Penny 

    Kaley Cuoco takes on the role of Leonard and Sheldon's neighbour, Penny. Like her co-star Johnny, she also started acting as a youngster and was cast at the age of 10 to play a young Karin Carter in the 1995 action thriller . Not long after, she was cast on the sitcom  and film 

    Kaley Cuoco began acting as a child

    Kunal Nayyar as Raj Koothrappali 

    Hapless Raj is played by Indian actor Kunal Nayyar. While studying business at university, Kunal took an interest in acting and found work doing American television ads and plays.

    While his only television credit prior to  is a small role on NCIS, he gained attention for his role in the play  where he portrayed an Indian exchange student.

     Kunal Nayyar plays Raj

    Simon Helberg as Howard Wolowitz 

    Playing Howard is Simon Helberg, who started his career as one part of a comedy duo with  creator Derek Waters. Before The Big Bang Theory, he appeared on the sketch comedy series  as well as  and 

    Simon Helberg started his career in a comedy duo

    Mayim Bialik as Amy Farrah Fowler 

    Mayim Bialik joined the cast in season three as neuroscientist Amy. In real-life, Mayim began life as a child actress, with roles in  and , but took a break from acting to study for a doctorate in neuroscience.

    Mayim Bialik studied neuroscience during a break in her acting career

    Melissa Rauch as Bernadette Rostenkowski-Wolowitz

    Howard's unlikely love interest Bernadette is played by Melissa Rauch, who actually began her television career in presenting roles. She was a regular contributor to VH1's  before being cast in Australian comedy  and the short-lived Lily Tomlin-led series 

    Melissa Rauch plays Bernadette

    Sign up to HELLO Daily! for the best royal, celebrity and lifestyle coverage

    By entering your details, you are agreeing to HELLO! Magazine User Data Protection Policy. You can unsubscribe at any time. For more information, please click here.

    ncG1vNJzZmivp6x7qbHLpaammZeWx6q6xGeaqKVfm7atuY5rZ2tqYG19dH2TcGhwbl%2BptaZ5waKeZpqRo7RuwMeepquxXZiutMCMrKuaqqRivKd506GcoqpdmK6zscSrqmaomKTBsL%2BO