Chuck Lorre’s Big Bang Theoryuniverse has tons of celebrity cameos throughout the original sitcom and its prequel spin-offs. Of course, considering the series mostly centers on a group of oddball geeks, these minor guest stars typically include famous nerd-culture heroes like Star Wars’ Mark Hamill, comic-book legend Stan Lee, and Trekkie Sheldon’s favorite half-human, half-vulcan on the USS Enterprise, Leonard Nimoy. While there are plenty of funny and sentimental special appearances like these, not many stars have been brought back to play multiple roles.