Who's your favourite big bad evil guy in a game you played?

[Grod_The_Giant]

I think my favorite was from a low-level 5e game I ran-- a revenant by the name of Balthazar Philips.

Mechanically he was great because there's no way to really stop a revenant. I never had to worry about his being threatened or killed early. He could get up in the party's face and piss them off all he wanted; if they cut him to pieces he'd just pop back up the next night.

Personality-wise, he was great because he was insanely petty and seriously overdramatic. You didn't really need to do anything to get him upset, and once he notices you pretty much anything you do just keeps making him more infuriated. (He also was greedy and vengeance-obsessed more than actively evil, so he was unlikely to start slaughtering innocents no matter how angry he got).

All of this adds up to a guy who figures out where the party is going next, rushes ahead, and spends two hours building a wooden gallows in the middle of nowhere so that he can make his entrance as a hanged body suddenly raising its burning eyes. He then proceeds to scream at them for five minutes about how they're ruining all his plans and killed his favorite ghoul and left muddy footprints on the floor when they searched his house before someone finally gets fed up and takes a swing at him. The party jumps in too, and he's down to single-digit hitpoints and totally surrounded by the time his first turn comes up. At which point he snarls something along the lines of "**** all of you," casts Fireball centered on his current position, and vaporizes himself along with the entire party. Literally everyone was down at dying; if the Cleric hadn't rolled a natural 20 on their first death save it would have been an actual TPK.