Spock was half-human, but culturally all-Vulcan — and, even so, he was the emotional heart of Star Trek.
Raised from a young age to valorize logic over emotion, but serving on a ship overwhelmingly populated by all-too-fallible humans. A stranger in a land that was strange to him, but familiar to everyone else. An outsider struggling to fit it, but also not entirely sure that he wanted to fit in. A figure of fun, but often in many ways superior to the more conventional characters surrounding him. He had difficulty relating to people, but always came through when needed. And his crewmates always came through for him. In short, a perfect stand-in for a nerdy audience — more socially awkward than we would ever be and yet exactly as indispensable as we hoped we would prove to be.
But there was always a Spock.
On The Next Generation — the best and most successful of the shows — the Spock role was filled by Brent Spiner's Data, an android trying to work with a bunch of biological shipmates. Deep Space Nine gave us Odo, the shapeshifter. Voyager initially struggled with Vulcan Lieutenant Tuvok as its Spock until the arrival of the character Seven of Nine as a former member of the Borg Collective trying to rediscover her originality. For Enterprise — the last Trek show produced but the first one in the fictional chronology — they finally gave us a lady-Spock in Vulcan Commander T'Pol, on loan from High Command to help out humanity.
The show could never ditch this conceit because the Spock character was, simply, too good. His lack of insight into human concepts of humor and fun could be, of course, extremely funny.
But in the hands of Stark Trek's writers, Spock's commitment to logic over emotion was the pinnacle of heroism rather than its antithesis. He deduced an ethic of rigorous utilitarianism and lived and died according to a profoundly moral code:
But Spock was not only a hero. He was a particular kind of hero. Someone the wrong kind of people would call a villain. I am always struck, as a longtime Star Trek fan, by the fact that many media figures seem to think it's a dis on President Obama to compare him to Spock:
The ease with which some deride Spock makes him truly unusual for a television character. Spock is someone who some of us can eminently identify with, but also someone who others find so alien that they are compelled to castigate him. That, in turn, makes him a dozen times more relatable than a more conventional and universally admired hero.
Spock's intelligence, bravery, courage, and good judgment don't win him the universal admiration of his crewmates or of the world. But he did earn their respect, and over time he accomplished most of what he set out to do, from saving their ship, the Enterprise, to brokering peace with the Klingons, to aiding Romulan dissidents.
He was an archetype that was compelling enough to power not just five Star Trek shows, but countless characters in subsequent decades' shows: from Rupert Giles in Buffy to Benedict Cumberbatch's version of Sherlock Holmes to Temperance Brennan in Bones to House's Dr. House.
Over time, that turned Spock into something of a cliché. But he was an original in the 1960s, and Leonard Nimoy's skill in defining the character helped define an entire genre of characters for generations to come.
And rightly so. Star Trek is beloved for good reasons, and Nimoy's Spock is at the top of what made it great.