Zombies are undead-type monsters in Titan Quest. They are usually located around Ruins, Caves and Graveyards. There are two types of them. Green-skinned zombies (Festering/Noxious/Putrescent), after being defeated, emit deadly poison clouds from their body, while their grey-skinned relatives (which are called Zombie Soldiers, Zombie Archers, Grotesque Zombies, Revolting Zombies) don't emit anything toxic.
Recommended resistances: Bleed, Poison, Pierce.
Notes: Zombies are very slow. Keep this in mind when fighting both zombies and another type of monsters- you can run away, kill the other type of monster, and then kill the zombies or run away if didn't killed to other monster type.