'Big Bang Theory': First look at Bob Newhart's guest appearance - Watch now


When Bob Newhart comes to "The Big Bang Theory," he'll be making Sheldon's dreams come true.

In a clip previewing the comedy legend's upcoming guest appearance on the CBS rating juggernaut, Newhart plays Professor Proton, the host of Sheldon ( Jim Parsons) and Leonard's ( Johnny Galecki) favorite childhood TV show, whom our favorite nerds have hired to perform for them.

Upon meeting quirky Sheldon, who can hardly contain his excitement, Professor Proton questions his biggest fan's sanity, asking Leonard, "Is he dangerous?"

The excitement wasn't limited to the filmed scene, either. Of Newhart's appearance, Parsons told The Hollywood Reporter, "It was incomprehensible; you can't comprehend what it is you're doing. We've had some great people on this set, but he was the first person that I had that feeling of, 'I can't believe you're real.'"

Newhart's "Big Bang Theory" debut will air Thursday, May 2 at 8 p.m. on CBS.
Photo/Video credit: CBS