Spock as a character is just freaking awesome. I mean, the Vulcans as a concept are fascinating. And obviously it's an exploration of the idea of repressing emotional reactions in favor of logic
and rationality*, which is intriguing by itself. Much better than the explanation of what vampires are an exploration of.
*deleted, as a comment pointed out this is incorrect
Also: This. This makes me so happy. (Image created by deviantartist Zink120 who wrote "I guess this is what happens if you watch The Big Bang Theory immediately after listening to party rock anthem!") If you don't see why that's awesome, I can't explain. Just. Trust me.
Who's your favorite science fiction alien or alien race? - in any science fiction universe!