We may receive a commission on purchases made from links. Throughout its 12-season, 12-year run, "The Big Bang Theory" featured a ton of guest stars — just the list of "Star Trek" veterans alone ...

From Sheldon's (Jim Parsons) eccentric antics to Leonard's (Johnny Galecki) outrageous escapades, the show's funniest ...

Then, at 18, Wheaton suddenly left Hollywood. He explains why he left and came back and how he came to play his evil self on The Big Bang Theory. Produced by Will Wei. Camera by Devan Joseph.