For me, it would be GLaDOS.
Portal 2 spoiler
She deleted the one remaining human part of herself because it was just too much to deal with. She releases you at the end of Portal 2 as a path of least resistance measure because “killing you is hard.”
What about you, what is your favorite media villain?
I don’t have one favorite villain in particular, but…
The Good Place spoilers
Michael is the villain for part of the series, and oh boy is he devilish. I mean, in season 2 (i think) he is literally the devil as far as the main cast is concerned. “I can’t believe you figured it out!” perfect delivery. Just wow.
oh, and also Megamind. Megamind is my favorite. I need to rewatch that movie, and completely ignore the “sequel”.