Zombies are undead beings created through the reanimation of human corpses that appear in The Mummy. They are the servants of Ahmanet and Set and appear to have some if not all of their memories from their past lives.
It should be noted that unlike most versions which are a result of science or a disease, these were lifeless corpses that were brought back through dark magic which may explain their superior intelligence and strength.
It is currently unknown if there is more then one type of Zombie.
The Zombies first appear when Ahmanet is released from her sarcophagus after the plane crash. Still physically weak from her mummification, she starts sucking the lifeforce from people to regain her lost powers. She then uses her powers to reanimate them as undead muscle which she uses to attack Nick and Jenny several times throughout the movie.
First using them to ambush Nick and restrain him in the church so that she could easily stab him with the Dagger of Set, Ahmanet then sent them after Nick and Jenny to recapture them after they managed to escape.
She later reanimates an army of undead English crusaders to gain entrance to the crypt by slaughtering everybody inside in order to regain the Egyptian ruby to complete her Dagger. She also used these to try and assassinate her rival for Nick's affections, Jenny, which proved unsuccessful after Nick chose to intervene.
Later, towards the end of the film, the Zombies were turned to dust after they were no longer needed by Ahmanet as they had already served their purpose.