Nimoy, Leonard
From The Big Bang Theory Wiki
Actor best known for playing the Star Trek character Spock. IMDb page
Sheldon is a huge fan of Nimoy and shows an overwhelmed, emotional response when Penny gives him a napkin signed by the actor as a Christmas present (0211).
Sheldon: All I need is a healthy ovum and I can grow my own Leonard Nimoy!
In an interview, Jim Parsons revealed that Nimoy sent two signed napkins after seeing the episode, which were later auctioned at a charity Nimoy had suggested (see the video and a picture of Jim showing the autograph here).
