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?
Ming the Merciless
as played by Max von Sydow in the 1980 film Flash Gordon
Ming is this potentially goofy over-the-top villain, but Sydow’s portrayal makes him dignified, threatening, majestic and malevolent, never laughable.
Same with Frank Langella’s performance as Skeletor in the terrible Masters of the Universe film
I only remember the animated series from my childhood on Saturday mornings