Adam Nimoy appears on tonight episode (5-November-2015) of The Big Bang Theory: The Spock Resonance. Adam Nimoy interviews Sheldon for a Star Trek documentary on how Spock influenced the life of Star Trek fans.

There are pictures of Adam Nimoy on the show on his credits page:

... and on the page for the episode:

Mr. Nimoy directed Z'ha'dum (1996) and Passing Through Gethsemane (1995).