Lord of the Accursed

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

Roaming Throne

Ward {2}
As Roaming Throne enters, choose a creature type.
Roaming Throne is the chosen type in addition to its other types.
If a triggered ability of another creature you control of the chosen type triggers, it triggers an additional time.

Wilhelt, the Rotcleaver

Whenever another Zombie you control dies, if it didn't have decayed, create a 2/2 black Zombie creature token with decayed. (It can't block. When it attacks, sacrifice it at end of combat.)
At the beginning of your end step, you may sacrifice a Zombie. If you do, draw a card.

Undead Augur

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

Gravecrawler

Gravecrawler can't block.
You may cast Gravecrawler from your graveyard as long as you control a Zombie.

Headless Rider

Whenever Headless Rider or another nontoken Zombie you control dies, create a 2/2 black Zombie creature token.

Rooftop Storm

You may pay {0} rather than pay the mana cost for Zombie creature spells you cast.

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.

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.)

Diregraf Colossus

Diregraf Colossus 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.

Diregraf Captain

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

Cleaver Skaab

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