I've met a few people on TVTropes who claim to be playing a villain role or something roughly cognate to one in real life, without having any particular higher-level reason for doing so in mind; the infamous Troper Tales pages are a particularly fruitful source of examples, although it's likely that a lot of the more extreme ones come out of attempts at trolling.
Even if we discount active attempts at deception, that site selects for people who spend a lot of time thinking about character types, and additionally has the right demographics for many of them to put an excessively high priority on looking cool; it's wise to take this sort of character identification with several grains of salt. As best I can tell the motivations involved aren't usually all that villainous relative to most external observers, but it's self-image that's at issue here.
"If you meet the Buddha on the road, kill him!"
When Edward Wilson published the book Sociobiology, Richard Lewontin and Stephen J. Gould secretly convened a group of biologists to gather regularly, for months, in the same building at Harvard that Wilson's office was in, to write an angry, politicized rebuttal to it, essentially saying not that Sociobiology was wrong, but that it was immoral - without ever telling Wilson. This proved, to me, that they were not interested in the truth. I never forgave them for this.
I constructed a narrative of evolutionary biology in which Edward Wilson and Richard Dawkins were, for various reasons, the Good Guys; and Richard Lewontin and Stephen J. Gould were the Bad Guys.
When reading articles on group selection for this post, I was distressed to find Richard Dawkins joining in the vilification of group selection with religious fervor; while Stephen J. Gould was the one who said,
"I have witnessed widespread dogma only three times in my career as an evolutionist, and nothing in science has disturbed me more than ignorant ridicule based upon a desire or perceived necessity to follow fashion: the hooting dismissal of Wynne-Edwards and group selection in any form during the late 1960's and most of the 1970's, the belligerence of many cladists today, and the almost ritualistic ridicule of Goldschmidt by students (and teachers) who had not read him."
This caused me great cognitive distress. I wanted Stephen Jay Gould to be the Bad Guy. I realized I was trying to find a way to dismiss Gould's statement, or at least believe that he had said it from selfish motives. Or else, to find a way to flip it around so that he was the Good Guy and someone else was the Bad Guy.
To move on, I had to consciously shatter my Good Guy/Bad Guy narrative, and accept that all of these people are sometimes brilliant, sometimes blind; sometimes share my values, and sometimes prioritize their values (e.g., science vs. politics) very differently from me. I was surprised by how painful it was to do that, even though I was embarrassed to have had the Good Guy/Bad Guy hypothesis in the first place. I don't think it was even personal - I didn't care who would be the Good Guys and who would be the Bad Guys. I just want there to be Good Guys and Bad Guys.
[Postscript, 2026: Since then, I've read Wynne-Edwards' last book arguing for group selection. IMHO it is a very bad book, and hooting dismissal of it is appropriate. Goldschmidt's theory of macroevolution may have been based on quick changes in the fossil record (I don't know), but we now have strong evidence this is due to cascades of rapid evolutionary change (punctuated equilibrium). I don't know what Gould was talking about re. the cladists. So I no longer think of Gould's statement as especially virtuous, which makes it a bad example for this post.]