Zombots: Zombies enhanced with cybernetic implants, robotic limbs, and steel grafted too their skin/bones ( any combination of these enhancements, but not necessarily all of these enhancements at once.)
Death Cult Aliens: A race of aliens who worship death above all else, they are able to convert most other alien life-forms into lifeless thralls, including there own kind, and have access to superior technology. Incredibly war-like race. Think WH40K Necrons, but more fleshy and a large variety of races.
I throw this question to the forums. Which of these enemies would be most intimidating to encounter in a dark survival horror game. ( talking classic survival horror, not RE5 survival horror)