These special guests appeared on The Big Bang Theory as themselves for some incredibly hilarious moments. Check them out!
We begin with the recently deceased cultural icon, Leonard Nimoy. In Season 5, the Star Trek star acted as the voice of Sheldon's rather opinionated Mr. Spock action figure.
In Season 2, Leonard, Howard, and Raj spot Summer Glau (Firefly, Serenity, The Terminator) on a train, and promptly all make fools of themselves.
Charlie Sheen makes an appearance in Season 2, when he and Raj have a brief encounter at The Cheesecake Factory.
In Season 3, Sheldon manages to get a restraining order against him by Stan Lee.
Best known for his role on Star Trek: The Next Generation, Wil Wheaton has made more than a few appearances, most of which involve him antagonizing Sheldon. He made his first appearance in Season 3.
Neil Degrasse Tyson
Neil Degrasse Tyson, astrophysicist and host of the show, Cosmos, appeared in Season 4.