As science fiction nerds, Leonard, Sheldon, Howard and Raj are all fans of Star Trek. There have been references made to the first four television series - Star Trek: The Original Series, Star Trek: The Next Generation, Star Trek: Deep Space Nine and Star Trek: Voyager - the first six films, Star Trek: First Contact, and J.J. Abram's 2009 reboot film, but none yet to the fifth and final television series Star Trek: Enterprise or directly to Star Trek: The Animated Series.Both Leonard and Sheldon agree that The Original Series is better than The Next Generation, but that Captain Picard of The Next Generation is superior to Captain Kirk of The Original Series. Sheldon believes that Star Trek: The Motion Picture was the worst movie and Star Trek IV: The Voyage Home was “inarguably the best,” while Raj believes Star Trek V: The Final Frontier to be the worst and Star Trek II: The Wrath of Khan to be the best. References to Star Trek in The Big Bang Theory are frequent. All four male main characters are fluent in Klingon and often play Boggle in the language. Leonard has everyday and dress Starfleet uniforms, Sheldon has a Spock uniform, and Raj has an Uhura uniform that Priya wears. All of them can recite Spock's dying words, and Sheldon has recited dialogue of Khan Noonien Singh as well as Picard's speech about drawing the line in Star Trek: First Contact. Sheldon, a self-proclaimed honorary graduate of Starfleet Academy and Captain Kirk of theoretical physics, introduces "Rock-Paper-Scissors-Lizard-Spock", invented by Sam Kass, and the guys always choose Spock. Sheldon has an adversarial relationship with Star Trek: The Next Generation star Wil Wheaton, who has appeared as a fictionalised version of himself on four occasions. Sheldon likes Mr. Data but Brent Spiner replaces Wheaton as his enemy. Sheldon invites LeVar Burton, TNG's Geordi La Forge, to his home for a raffle, but he comes too late for anyone to notice him. Meanwhile, George Takei has appeared to Howard in his mind. Leonard has mentioned the Romulan Neutral Zone. The constant references to Star Trek seem to have had some influence on Penny, who was shocked when she referenced deflector shielding to Alicia in The Dead Hooker Juxtaposition. She also mentioned that her shields were up below the waist when she spent the night in Sheldon's bed in The Love Car Displacement.
Star Trek is the most mentioned thing in the series