Death Baron

Skeletons you control and other Zombies you control get +1/+1 and have deathtouch.

Escaped Null

Lifelink
Whenever Escaped Null blocks or becomes blocked, it gets +5/+0 until end of turn.

Feral Ghoul

Menace
Whenever another creature you control dies, put a +1/+1 counter on Feral Ghoul.
When Feral Ghoul dies, each opponent gets a number of rad counters equal to its power.

Gray Merchant of Asphodel

When Gray Merchant of Asphodel enters the battlefield, each opponent loses X life, where X is your devotion to black. You gain life equal to the life lost this way. (Each {B} in the mana costs of permanents you control counts toward your devotion to black.)

Graveborn Muse

At the beginning of your upkeep, you draw X cards and you lose X life, where X is the number of Zombies you control.

Champion of the Perished

Whenever another Zombie enters the battlefield under your control, put a +1/+1 counter on Champion of the Perished.

Bladestitched Skaab

Ebondeath, Dracolich

Flash
Flying
Ebondeath, Dracolich enters the battlefield tapped.
You may cast Ebondeath, Dracolich from your graveyard if a creature not named Ebondeath, Dracolich died this turn.

Eternal Skylord

When Eternal Skylord enters the battlefield, amass Zombies 2. (Put two +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.)
Zombie tokens you control have flying.

Blackcleave Goblin

Haste
Infect (This creature deals damage to creatures in the form of -1/-1 counters and to players in the form of poison counters.)

Grimgrin, Corpse-Born

Grimgrin, Corpse-Born enters the battlefield tapped and doesn't untap during your untap step.
Sacrifice another creature: Untap Grimgrin and put a +1/+1 counter on it.
Whenever Grimgrin attacks, destroy target creature defending player controls, then put a +1/+1 counter on Grimgrin.

Archghoul of Thraben

Whenever Archghoul of Thraben or another Zombie you control dies, look at the top card of your library. If it's a Zombie card, you may reveal it and put it into your hand. If you don't put the card into your hand, you may put it into your graveyard.

Cemetery Reaper

Other Zombie creatures you control get +1/+1.
{2}{B}, {T}: Exile target creature card from a graveyard. Create a 2/2 black Zombie creature token.

Cleaver Skaab

{3}, {T}, Sacrifice another Zombie: Create two tokens that are copies of the sacrificed creature.

Diregraf Captain

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

Corpse Harvester

{1}{B}, {T}, Sacrifice a creature: Search your library for a Zombie card and a Swamp card, reveal them, put them into your hand, then shuffle.

Carrion Feeder

Carrion Feeder can't block.
Sacrifice a creature: Put a +1/+1 counter on Carrion Feeder.

The Scarab God

At the beginning of your upkeep, each opponent loses X life and you scry X, where X is the number of Zombies you control.
{2}{U}{B}: Exile target creature card from a graveyard. Create a token that's a copy of it, except it's a 4/4 black Zombie.
When The Scarab God dies, return it to its owner's hand at the beginning of the next end step.

Diregraf Colossus

Diregraf Colossus enters the battlefield 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.