Taken from the old Marvel Universe definition:
Known Superhuman Powers: As a zombie, Simon Garth possessed certain supernatural abilities derived from the loa (voodoo spirits) which inhabited and reanimated his form after death. Garth was not a typical zombie, however. For reasons beyond explanation, his spirit never fully left his body at death. Hence, at times, Garth's persona was able to assume partial control over his body's actions. This occurred only when the Zombie encountered situations which had heavy emotional connections to his mortal life.
Simon Garth's lifeless, reanimated body possessed a supernatural healing ability, enabling him to regenerate missing or injured tissue or mend broken bones. Thus he could fully recover from small burns, lacerations, and gunshot wounds within a matter of hours. The Zombie could not regenerate missing limbs, although a severed limb pressed against the area it came from would probably reattach itself. A zombie's flesh can be burned so totally that it cannot recover. To facilitate regeneration (and to prevent their bodies from rotting away completely), zombies have to consume the fleshy tissue of recently killed animals or human beings at least once per week. Not truly alive, zombies are immune to certain other mortal vulnerabilities, including suffocation, extremes of temperature and pressure, high voltage electricity, and poisonous gas. Garth's Zombie once walked the ocean floor without harm.
Zombies possess neglible brain activity and thus no reasoning, memory, or sensory capacities. They cannot see, hear, smell, taste, or feel. Zombies are impervious to pain. Instead of mortal senses, the Loa animating a zombie grant it certain primitive mystical senses. Most developed of these is a zombie's ability to perceive the call of its master, motivating it to move in that direction. Garth wore an amulet around his neck and could be verbally commanded by anyone in possession of its counterpart. Since zombies are incapable of independent thought, they cannot speak of their own accord. They can, however, respond in a designated manner if their master so directs them. The lingering presence of his spirit enabled Garth to speak independently on extremely rare occasions.
Zombies are vulnerable to the voodoo which gives them animation. The proper incantation and treatment of a voodoo doll can cause supernatural, debilitating pain to a zombie. A zombie can also be put to rest through the appropriate voodoo ceremony which forces the loa from his body.