A Basic Enemies Guide for Sniper Elite: Nazi Zombie Army.
Not Completed, Planning too add more details on each enemy whenever i(Or someone wants too) can get around to it.

Slow, Melee, Average
Effective Weapons: Anything, really.
Useful Tactics:
Range: Grunts are your generic brain-dead zombie, keep your distance and you get to keep your brain.
Movement: Grunts can be out-runned/out-jogged simply by moving allowing you to get good shots off on the Grunts without being in hitting distance.

Fast, Medium AOE(Explosive), Weak
Effective Weapons: Pistols, Traps, SMG's
Useful Tactics:
Trigger Dash: Sprint past the Suicider close enough to clip his shoulder with yours, this will activate his attack causing him to stop and explode, at this point you keep running past him outside of the blast radius.
Sniping: IF you can get a Suicider through a doorway or a hallway the Sniper can be your best bet for taking them down, 1 round from a bolt action should kill the Suicider at a distance keeping you(and your team-mates) outside of his blast radius.

Fast, Melee, Strong
Effective Weapons: Webley, Traps, Shotguns, Explosives
Useful Tactics:
Movement: Skeletons can be out-runned leaving a opening for you to get some shots off.
Traps: Due to Skeletons fast movement they can be hard to hit with any SMGs or Snipers, Trip Mines and Landmines are key to taking down any that you can’t hit.

Slow, Ranged, Strong
Effective Weapons: Webley, Traps, Shotguns, Explosives
Useful Tactics:
Traps: Due to Heavy's slow movement and ranged attacks they can be hard to hit with with SMG's or Pistols, Trip Mines and Dynamines(Dynamite + Land Mine) will make short work of any Heavy's you come across.
Distance: Heavy's move insanely slow and in predictable paths allowing easy Sniping from a distance.

Slow/Static, Ranged, Average
Effective Weapons: Sniper
Useful Tactics:
Headshots: nuff said(Remember mouse wheel while in scope will increase the zoom!)

Static, Summoner, Strong X3
Effective Weapons: Sniper, Panzer Faust, Webley
How To:
Line up a skull which float around him,(DO NOT chase the skulls around him) and take it out, after all skulls have been destroyed he will turn Solid(not Ghost form), repeatedly shoot him in the head with your Sniper/Guns.