Here are all the Star Trek actors who appeared in The Big Bang Theory. With the sitcom rooted in the male cast's love for everything nerdy, comic book and other pop culture franchises were often featured on the show. Thanks to Sheldon's (Jim Parsons) personal fondness of it, the CBS show incorporates as many references as they could in its 12-year-run with some cast members of various Star Trek projects appearing in the sitcom.
Created by Gene Roddenberry in the mid-60s, Star Trek has grown exponentially over the years with a string of movie and TV projects in its portfolio. Sheldon, Leonard (Johnny Galecki), Howard (Simon Helberg), and Raj (Kunal Nayyar) can all speak fluent Klingon and recite Spock's final words. They typically throw various references about the franchise in their normal conversations, with Sheldon mostly always kickstarting it.
Given the male characters' fondness for Star Trek, it makes sense that The Big Bang Theory's executives tried to bring in as many prominent actors from the sci-fi property as they could. They, however, put a spin on this guesting stints by having some of them play themselves, while others were cast to portray different characters.
Wil Wheaton
Essentially a recurring guest star in The Big Bang Theory, Will Wheaton, who plays Wesley Crusher in Star Trek: The Next Generation, debuted as himself in season 3, episode 5 titled "The Creepy Candy Coating Corollary" after he joins the Mystic Warlords of Ka'a tournament with Stuart (Kevin Sussman). This gave Sheldon the idea to confront him for skipping the '95 Dixie Trek Convention in Jackson, Mississippi where he was waiting to see him. For a while, the pair become arch-enemies, resulting in Wheaton's regular appearance in The Big Bang Theory until its final year. By season 5, they patch things up and become good friends - so much so that Sheldon is willing to ditch his then-girlfriend Amy (Mayim Bialik) to hang out with Wheaton.
Leonard Nimoy
As a devoted Trekkie, Sheldon has an undying devotion to Leonard Nimoy, who plays half-Vulcan Spock in the original Star Trek movies and television series. While Nimoy never appeared in person on The Big Bang Theory, he voiced a Spock action-figure in season 5, episode 20 titled "The Transporter Malfunction", who advises Sheldon to use his transporter despite it being in mint condition. Later on, the Nimoy figure returns and reprimands the socially-inept genius for his switching his broken toy with Leonard's. The back-and-forth between Parsons and Nimoy was hilarious as the toy changed positions every single time the camera panned to it. Before his voice cameo in the series, Penny (Kaley Cuoco) also gifted Sheldon Nimoy's used and signed napkin from when he visited The Cheesecake Factory. It is one of the most iconic Sheldon moments in The Big Bang Theory's run. It's worth noting that Leonard Nimoy's son, Adam Nimoy, also appeared on the show back in season 9, episode 7 titled "The Spock Resonance."
Brian George
Playing Julian Bashir's (Alexander Siddig) father in the Star Trek: Deep Space Nine episode "Doctor Bashir, I Presume" Brian George is a familiar face for The Big Bang Theory fans. Like his stint in the '90s Star Trek TV show, the actor also portrayed a father-figure in the CBS sitcom, playing Raj's Indian-based father, V.M Koothrappali. A gynecologist by profession, he first appeared in season 1, episode 8 titled "The Grasshopper Experiment" as he checks-up on Raj, who was still struggling with selective mutism at that time. Often appearing via a video call, the Koothrappali patriarch set up Raj with Anu (Rati Gupta) in The Big Bang Theory final season, and he's quite pissed when he found out that the wedding is canceled.
Mark Harelik
Appearing in the Star Trek: Voyager episode titled "Counterpoint" as Kashyk, Mark Harelik played Dr. Eric Gablehauser in The Big Bang Theory. Debuting in season 1, episode 4 titled "The Luminous Fish Effect" as the head of the Physics Department at CalTech and was the initial boss of Sheldon, Leonard, and Raj. The character only appeared five times between seasons 1 and 2 where he also introduced child prodigy Dennis Kim, much to Sheldon's distress. Due to a conflict with Sheldon, Gablehhauser got to meet Mary Cooper (Laurie Metcalf), with the two surprisingly striking a weird kinship with each other, although nothing came out of that initial encounter.
LeVar Burton
Known for his stint on Star Trek: The Next Generation playing Georgi La Forge, LeVar Burton as himself first appeared on The Big Bang Theory season 4, episode 17 titled "The Toast Derivation" after he's invited to Sheldon's party for his new friends. The pair missed each other though, as, by the time Burton arrived at the apartment, Sheldon has left already to reconcile with his original pals. The actor returned in season 5, episode 7 titled "The Habitation Configuration" as Sheldon and Amy's guest for "Fun with Flags." Burton's final appearance in The Big Bang Theory is in season 8, episode 10 titled "The Champagne Reflection" where he's once again a guest for Sheldon's web-info series.
Brent Spiner
Playing the android Data on Star Trek: The Next Generation and four following movies, as well as the ongoing Star Trek: Picard, Brent Spiner appeared as himself on The Big Bang Theory. In season 5, episode 5 titled "The Russian Rocket Reaction," he attends Wil Wheaton's party. Sheldon and his friends are also in attendance, and it's where Wheaton gives him a signed, unopened limited edition Wesley Crusher action figure to make up for missing '95 Dixie Trek Convention. While the pair hug it out, Brent Spiner comes in and spots the mint collectible, grabs it from Sheldon's hands, and quickly rips it open. This causes Sheldon to put him on his enemy list.
George Takei
Howard's star-studded dream in The Big Bang Theory season 4, episode 4 titled "The Hot Troll Deviation" featured George Takei as himself, alongside Katee Sackhoff. In the sequence, the aerospace engineer is amid his self-pleasing fantasy, which initially only involves Sackhoff. Eventually, Takei also appears when the idea of Howard being bi-sexual comes up. He and Sackhoff stick around until later in the episode as they coach Howard on his date with Bernadette (Melissa Rauch). The veteran actor played Captain Hikaru Sulu in the Star Trek: The Original Series, as well as the original movies.
William Shatner
For years, fans were waiting to see William Shatner in The Big Bang Theory, but it never happened until the final season. Known for his role as Captain James T. Kirk in the Star Trek franchise, Sheldon meets the actor via Wil Wheaton's Dungeons and Dragons game night who is among the high-profile guest participants such as Joe Manganiello, Kareem Abdul-Jabbar, and Kevin Smith. As expected, Sheldon gets a little too excited upon meeting Shatner causing some funny exchanges between the pair. In the end, just like Sheldon and the boys, fans are pleased that The Big Bang Theory was able to feature Shatner before it officially wrapped up.