Ever since it first aired back in 1966, there's been one thing Star Trek has done consistently well, and that is create imaginative and interesting villains. Between brutal alien races, remorseless robot forces, and the occasional rogue madman, the franchise is packed to the brim with bad guys who make the universe all that more interesting.
And with our plucky heroes having a multitude of skills in their own right, it makes sense that said bad guys would also come packing more than a little in terms of power. Indeed, many enemies of unimaginably powerful, either because they've created a military stronghold in the universe, or because they were just blessed with crazy space powers.
Not only does this work wonderfully to make us support the Captain and crew unfortunate enough to cross paths with these monsters, but it also serves to make for a much more morally grey universe, as we see these powerful villains use their abilities for terrible things that are entirely justifiable in their own minds.
Every villain in Star Trek is the hero of their own story, even if they decide to annihilate two galaxies on the way, and that's half of what makes them so damn scary - well, that and the fact that they're capable of destroying a galaxy in the first place.
10. Charlie X
What happens when you give a seventeen year old who's been isolated for most of his life incredible powers, seemingly over reality itself?
Well, in the case of Charlie, it turns out you get a rather big problem. Bestowed with unimaginable power from the Thasians, it quickly becomes clear that Charlie intends to use his new abilities for less than stellar purposes - especially when he begins to react violently towards Yeoman Rand when she doesn't return his "romantic" gestures.
Indeed, the crew are largely unable to stop Charlie, as he is able to change reality around them to gain the upper hand any time anyone tries. Had the Thasians not come back to claim their mistakes, it seems almost sure that the Enterprise's unfortunate crew might have still been under the young man's control - if he allowed any of them to live after growing tired of them.