7. Spider Slicer from Bioshock 2

That rabbit mask is actually terrifying. 

These guys are mostly annoying because they make you waste a whole ton of ammo.  They can also come out of nowhere and freak you out if you’re not paying enough attention.  Even more annoying, is that they’ll try to use Health Stations. 

Personally, I hate enemies that heal themselves.  It makes them shoot to the top of the most hated list.