Wayward Servant

Whenever another Zombie you control enters, each opponent loses 1 life and you gain 1 life.

Ratadrabik of Urborg

Vigilance, ward {2}
Other Zombies you control have vigilance.
Whenever another legendary creature you control dies, create a token that's a copy of that creature, except it's not legendary and it's a 2/2 black Zombie in addition to its other colors and types.

Tormod, the Desecrator

Whenever one or more cards leave your graveyard, create a tapped 2/2 black Zombie creature token.
Partner (You can have two commanders if both have partner.)

Poxwalkers

Deathtouch
Curse of the Walking Pox — Whenever you cast a spell from anywhere other than your hand, return this card from your graveyard to the battlefield tapped.