Wayward Servant

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

Accursed Marauder

When this creature enters, each player sacrifices a nontoken creature of their choice.

Diregraf Captain

Deathtouch
Other Zombie creatures you control get +1/+1.
Whenever another Zombie you control dies, target opponent loses 1 life.

Retrofitted Transmogrant

{3}{B}: Return this card from your graveyard to the battlefield tapped with two +1/+1 counters on it.

Mindless Conscription

When this enchantment enters and whenever you draw your third card each turn, amass Zombies 3. (Put three +1/+1 counters on an Army you control. It's also a Zombie. If you don't control an Army, create a 0/0 black Zombie Army creature token first.)

Varina, Lich Queen

Whenever you attack with one or more Zombies, draw that many cards, then discard that many cards. You gain that much life.
{2}, Exile two cards from your graveyard: Create a tapped 2/2 black Zombie creature token.

Diregraf Colossus

This creature enters with a +1/+1 counter on it for each Zombie card in your graveyard.
Whenever you cast a Zombie spell, create a tapped 2/2 black Zombie creature token.

Death Baron

Skeletons you control and other Zombies you control get +1/+1 and have deathtouch. (Any amount of damage they deal to a creature is enough to destroy it.)