Jim Parsons (Sheldon Cooper)

As Sheldon Cooper, the nerdy, scene-stealing roommate who turned the sitcom into one of the most watched shows on television, Jim Parsons played a huge part in making The Big Bang Theory what it is today. He's also the reason why it ended, reportedly. After 279 episodes, which is considered one of the most in multi-camera show history, The Big Bang Theory ended because Parsons ultimately refused to sign a contract for Seasons 13 and 14 totaling in $50 million (!), believing he had done everything he would want to do with this character after 12 seasons. The series thus ended in May 2019. Nevertheless, he continues to play Sheldon in voice only on Young Sheldon, the single-camera prequel series. Since the show ended, he was heard in an episode of The Simpsons. He'll also play a role in Ryan Murphy's newest show, Hollywood, premiering in May.