Metroid - Samus in the CDI

Yeah, maybe she is more ruthless than the Doomslayer. At least the Doomslayer only kills demons because they are chaotic evil by default, but this thing was doing nothing, it was just minding it's own business and didn't attacked until it was attacked. She is fucking cool and ruthless.

This thing will attack you regardless of whether or not you fight back.

Doomguy/slayer is a centuries old demi god of death, I'm quite sure he's more violent.