Willrow Hood/Shutterstock

What's now known as "Star Trek: The Original Series" launched in 1966, which is about six decades ago now. It's the magnum opus of American screenwriter and producer Gene Roddenberry, who also went on to create other sci-fi shows that were, unfortunately, not as iconic as "Star Trek." Over the decades, "Star Trek" has spanned many TV shows, movies, books, video games, and comics. James Tiberius Kirk remains the biggest face of the franchise and has been played by William Shatner and several other actors throughout the years. But there's one more character who is just as legendary, if not more: Spock.

Spock is the half-human and half-Vulcan science officer of the USS Enterprise. He is well-known for having a genius-level intellect and cold Vulcan logic, and that naturally goes against his emotional human nature. Ironically, this makes him highly relatable and interesting. He is perhaps one of the most quotable characters in sci-fi, with such epic lines as "Live long and prosper" and "The needs of the many outweigh the needs of the few."

The role of Spock has evolved throughout the character's appearances in the TV shows and movies. Three main actors have taken up the mantle of Spock, and all of them brought their own flavor and nuance to the character. While none of them are hated, some of the actors are more loved than others.

Zachary Quinto is the second main actor to take on the role of Spock. His breakout role was that of Sylar, the psychotic villain from the NBC superhero show "Heroes," which ran from 2006 to 2010. Quinto played Spock in the 2009 reboot movie "Star Trek," which is the highest-rated "Star Trek" movie ever, as well as its sequels "Into Darkness" and "Beyond." These movies don't take place in the same universe as "The Original Series," but in an alternate version known as the Kelvin Timeline.

Quinto was a good Spock, and it showed; he made the conflict between his two sides resonate with audiences. You can see it in the way Spock suppresses his human emotions after watching his mother die while Vulcan (his home world) gets destroyed. Later on, Spock takes out his rage on Kirk (Chris Pine) after he's taunted about the incident, with Quinto bringing out an angry and visceral reaction that is captivating.

Unfortunately, Quinto's time with the character wasn't long. The other Spocks had time to flesh out the role over several seasons of TV shows, while we only got Quinto for three movies that were spaced years apart. Over the course of the series, we saw Spock continuously embracing his human side, especially through his friendship with Kirk and romance with Uhura (Zoe Saldaña). It would have been interesting to see where Quinto went with that.

Compared to Quinto, Ethan Peck was an unknown actor when he was cast in the iconic role of Spock in August 2018. This wasn't in a reboot of the original series, but a prequel that actually takes place in the Prime Timeline. He would be appearing as a young Spock as a recurring character in the second season of "Star Trek: Discovery." He plays the adoptive brother of the main character, Michael Burnham (Sonequa Martin-Green), with whom he has a sibling rivalry.

He would later play Spock in a main role in the 2022 spin-off series "Star Trek: Strange New Worlds." It takes place a decade before "Star Trek: The Original Series." Spock is in his usual role as the science officer of the USS Enterprise, which is captained by Christopher Pike (Anson Mount). Even though he is the third main actor to play Spock, Peck managed to do his own thing with the character instead of trying to do an impression of the Spocks that came before him. This is a Spock that isn't fully in control of his emotions, so Peck has had the unique opportunity to show more of his human side. Still, Peck pays homage to the person who is responsible for the mature Spock we all know.

There may be more Spocks to come, but it's highly doubtful that any of them will ever take the number one spot from the man who defined the role: the late Leonard Nimoy. He played Spock across three seasons and 79 episodes of "Star Trek: The Original Series" from 1966 to 1969. He also reprised the role in six original-cast movies, from 1979 to 1991, and two of the Kelvin Timeline movies, from 2009 to 2013. Nimoy landed the role of Spock as a struggling actor. The character made the NBC executives uncomfortable — his ears were too devilish. He would have been axed from the show if Roddenberry hadn't fought for him.

Spock quickly became popular, forcing the powers that be to make him an essential part of the show. While Nimoy did not create Spock, he built him. That cold, emotionless, logical demeanor, deadpan delivery, the Vulcan salute, the duality that drives his internal conflict between his human and Vulcan sides, and most of what we have come to know and love about Spock wouldn't be possible without Nimoy.

By season two, Spock had become more popular than Kirk. There were fan clubs, magazine covers, and all manner of merchandise. He became the show to the point that Shatner feared for his future, since fans demanded more Spock and Roddenberry obliged. Eventually, Roddenberry made Shatner realize Spock's popularity benefited everyone, even Shatner himself. Kirk and Spock's friendship became the emotional anchor of the show. So it's not a stretch to say Nimoy was the best thing to ever happen to "Star Trek."