Lord of the Undead

Other Zombie creatures get +1/+1.
{1}{B}, {T}: Return target Zombie card from your graveyard to your hand.

Necromancer's Covenant

When Necromancer's Covenant enters the battlefield, exile all creature cards from target player's graveyard, then create a 2/2 black Zombie creature token for each card exiled this way.
Zombies you control have lifelink.

Time to Reflect

Exile target creature that blocked or was blocked by a Zombie this turn.

Inspiring Leader

Commander creatures you own have "Creature tokens you control get +2/+2."

Tomb Tyrant

Other Zombies you control get +1/+1.
{2}{B}, {T}, Sacrifice a creature: Return a Zombie creature card at random from your graveyard to the battlefield. Activate only during your turn and only if there are at least three Zombie creature cards in your graveyard.

Undead Warchief

Zombie spells you cast cost {1} less to cast.
Zombie creatures you control get +2/+1.

Zombie Master

Other Zombie creatures have swampwalk. (They can't be blocked as long as defending player controls a Swamp.)
Other Zombies have "{B}: Regenerate this permanent."

Graf Harvest

Zombies you control have menace. (They can't be blocked except by two or more creatures.)
{3}{B}, Exile a creature card from your graveyard: Create a 2/2 black Zombie creature token.

Grave Betrayal

Whenever a creature you don't control dies, return it to the battlefield under your control with an additional +1/+1 counter on it at the beginning of the next end step. That creature is a black Zombie in addition to its other colors and types.

Endless Ranks of the Dead

At the beginning of your upkeep, create X 2/2 black Zombie creature tokens, where X is half the number of Zombies you control, rounded down.

Unholy Grotto

{T}: Add {C}.
{B}, {T}: Put target Zombie card from your graveyard on top of your library.

Zombie Infestation

Discard two cards: Create a 2/2 black Zombie creature token.

Anikthea, Hand of Erebos

Menace
Other enchantment creatures you control have menace.
Whenever Anikthea enters the battlefield or attacks, exile up to one target non-Aura enchantment card from your graveyard. Create a token that's a copy of that card, except it's a 3/3 black Zombie creature in addition to its other types.

Death Baron

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

Liliana's Mastery

Zombies you control get +1/+1.
When Liliana's Mastery enters the battlefield, create two 2/2 black Zombie creature tokens.

Risen Executioner

Risen Executioner can't block.
Other Zombie creatures you control get +1/+1.
You may cast Risen Executioner from your graveyard if you pay {1} more to cast it for each other creature card in your graveyard.

Dreadhorde Invasion

At the beginning of your upkeep, you lose 1 life and amass Zombies 1. (Put a +1/+1 counter 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.)
Whenever a Zombie token you control with power 6 or greater attacks, it gains lifelink until end of turn.

Undead Augur

Whenever Undead Augur or another Zombie you control dies, you draw a card and you lose 1 life.

Lord of the Accursed

Other Zombies you control get +1/+1.
{1}{B}, {T}: All Zombies gain menace until end of turn.

Boneknitter

{1}{B}: Regenerate target Zombie.
Morph {2}{B} (You may cast this card face down as a 2/2 creature for {3}. Turn it face up any time for its morph cost.)

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.