"All I know is logic."
―Spock, The Spock Resonance
Spock is a major character in the original Star Trek series. He is the science officer and first officer on the starship USS Enterprise, motivated to be logical, known for extremely repressed emotions, and high intelligence. This behavior results in him being a source of inspiration for Sheldon Cooper.
Spock is the Star Trek character that Sheldon most identifies with since he feels they are both intelligent, logical and unemotional. He was played by Leonard Nimoy in the original series of Star Trek, who reprised his role as Spock in The Big Bang Theory.
Appearance/References in TBBT
In Sheldon's first dream, Spock reasons with and convinces Sheldon to play with the vintage mint-in-box 1975 Mego Star Trek Transporter, which is a gift from Penny. Sheldon rapidly wakes up from his dream, opens the box and plays with the toy. But he breaks the toy shortly after and switches it with Leonard's.
In Sheldon's next dream, Spock says he's very disappointed in Sheldon and bids Sheldon to do the right thing. When Sheldon refuses, he is attacked by a Gorn in the dream.
In "The Codpiece Topology", the guys return to The Renaissance Fair with Sheldon portraying a Vulcan Star Fleet science officer (probably Spock) from a landing party observing a planet that resembled middle-ages Earth which also included strange modernistic anomalies which Sheldon had noted on their first visit.
The real life son of Leonard Nimoy, Adam, produces a documentary on Star Trek fans and interviews Sheldon, who shows them the napkin that Penny got his father to sign. Adam was working on a real documentary that premiered at the Tribeca Film Festival.
When Sheldon describes their group as a Star Trek landing party, he is Spock, Leonard is Kirk, Howard is Scotty and Raj is the guy in the red shirt that is killed or is Lt. Uhura.
Leonard Nimoy, Spock's original voice, died from complications from COPD (chronic obstructive pulmonary disease) on February 27, 2015.