What's your favourite FPS Villain?

[Drac]

The concept is simple enough, list one of your favourite game villains.

It could be an end chapter boss, or a just some random enemy type in a game that's really annoyed you like the floating skulls in doom. However, like all games, there are a few rules...

Rules

1. One Villian at a time! (you can post multiple times, but gives other a chance to jump in).
2. You cannot repeat a Villain someone else has already listed.
3. You must provide a screenshot/image/video/link of some kind.
4. You must mention the game the villain appears in, in case some haven't played it.

So, let's kick this off with perhaps the most obvious:



GLaDOS from Portal 2.

Wallpaper by Zeptozephyr

[Spectre8]

Well of course the first one that came to mind when I read the thread title was Glados

But seeing as there are rules about these things...



Shodan from System Shock gave me nightmares I guess that's plenty good enough reason to be up there