Zombies strength depends on what round you're on. In the early rounds, it takes only 5 M1911 clips in the body, 8 in the legs, to kill one without headshots. Later on, however, it could take an upwards of about 2-3 Ray Gun shots. Headshots are the most effective way to kill one, but body shots still work.
Most of the Zombies you encounter are Nazis, but since Shi No Numa, Nazi Zombies have been replaced in other maps.
To be straight, here are the apperances of Nazi Zombies:
- Nacht Der Untoten
- Zombie Verruckt
- Der Riese
- Kino Der Toten
Japanese zombies appear in Shi No Numa. American Zombies appear to attack the Pentagon is "Five". Russian zombies appear in Ascension and can be considered one the most difficult types of zombies to hit at times, rolling towards the player or strafing the the other direction of shots.
In Kino Der Toten and Five, gas zombies appear, which are crawling zombies that explode into Nova Gas upon death.
Also, there are Hell Hounds, the Pentagon Thief, Space Monkeys, The Cosmic Silverback and George A. Romero.