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 think the counter to that is that:
Tap for spoiler
they completely dropped the ball with her toward the end of the show. She went from, I think, a great allegory for a religious radical right wing capitalizing off her people’s suffering but in a way she could genuinely warp her beliefs into thinking was for the greater good…
… to, I mean, come on… Having her go totally crazed with power and disavowing the Prophets wasn’t the problem; it’s that it was stupid, egregiously paced, totally unearned MacGuffin power without grounded stakes that only served to make an already-rushed resolution to the show feel even more rushed.