Seven Guest Stars Who Blew Our Minds on The Big Bang Theory

Charlie Sheen! Stan Lee! Bill Nye! Watch our favorite surprise celeb moments from the series

BILL NYE

Beloved Bill Nye the Science Guy appears on episode 7 of season 7 when Sheldon attempts to use the famous scientist to make Dr. Arthur Jeffries (recurring guest star Bob Newhart) jealous after he chooses Leonard for a project over him. "Back off bow tie," yells the professor, who is anything but jealous.