"The Big Bang Theory" Cast: Then and Now

During its over 10 year run, many characters appeared on The Big Bang Theory - from the regulars to one-time guest stars - we’ve grown to love pretty much every character that appeared on the show. Have you ever wondered what they do other than play the colorful characters we've grown to know and love? Look no further! From Leonard Hofstadter to Wil Wheaton, Sheldon to Rajesh, have all the answers you could possibly want, right here.

While Sheldon is probably the first character that comes to mind when The Big Bang Theory is mentioned, it's Leonard who was originally framed as the show's main character - so we think it's fitting to start with him. Leonard is a talented experimental physicist with very nerdy leanings: he loves video games, comics and D&D. The series starts when Leonard, who has Sheldon Cooper as a roommate, falls desperately in love with beautiful neighbor Penny. Leonard has a good understanding of social norms and behaviours, but his friends' and roomate's actions constantly get in the way of him tryin to live the life he wants.

The role of Leonard is not the first one for Galecki, but it is the biggest one he's ever had.

While today, Galecki is best known for his portrayal of Leonard, he first started out with another extremely popular sitcom: Roseanne!

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Galecki played David Healy for the first 5 seasons of the show - but his role there was eclipsed by TBBT. Galecki's salary grew with the TBBT's popularity, and he's currently earning around $1 million per episode - one of the highest TV actor salaries in history.

Alessandra plays Claire, a cute bartender who asks Raj for help with the science fiction movie she's writing. Raj helps her out and falls for her in the process, ending up dating her….and Emily Sweeny, a macabre dermatologist who likes "cutting thing" - at the same time. Raj is torn about two-timing both of these women, and after a long, torturous bout of self flagellation, he decides to break up with them both.

Alessandra Torresani is no stranger to television - she even landed a lead role in another geeky TV show - the Battlestar Galactica science fiction spinoff series, Caprica. Other than her role in The Big Bang Theory, she had a string of appearances in other succesful TV shows, including Two and a Half Men, Husbands and American Horror Story. It seems like Torresani's star is on the rise, and she recently starred in Netflix's comedy movie, Step Sisters.

Stephanie first appears in the show’s second season as a doctor at a hospital Howard visits. Howard tries to seduce her by taking her to his workplace, where he lets her drive the Mars Rover around - but when she accidentally drives the Rover into a ditch, Howard freaks out and asks Leonard to drive her home. Unfortunately for everyone, Leonard and Stephanie end up hooking up in Leonard's car, and Stephanie and Leonard enter a comitted relationship far too quickly.

Johnny Galecki isn't the only Roseanne alum on The Big Bang Theory. When she was a kid, Sara Rue played a very young Roseanne on the show, in a scene depicting Roseanne's first meeting with Dan at a dance. Since leaving TBBT, she's appeared in guest roles in many other television shows; We’ve seen her as Brenda in Rules of Engagement, Kim Sallinger in Malibu Country and Candice in Mom.

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As of 2018, she can be seen in a recurring role on Netflix's A Series of Unfortunate Events.