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.

Anurid Murkdiver

Swampwalk (This creature can't be blocked as long as defending player controls a Swamp.)

Agent of Erebos

Constellation — Whenever Agent of Erebos or another enchantment you control enters, exile target player's graveyard.

Aphetto Vulture

Flying
When Aphetto Vulture dies, you may put target Zombie card from your graveyard on top of your library.

Jarad, Golgari Lich Lord

Jarad, Golgari Lich Lord gets +1/+1 for each creature card in your graveyard.
{1}{B}{G}, Sacrifice another creature: Each opponent loses life equal to the sacrificed creature's power.
Sacrifice a Swamp and a Forest: Return Jarad from your graveyard to your hand.

Glissa, the Traitor

First strike, deathtouch
Whenever a creature an opponent controls dies, you may return target artifact card from your graveyard to your hand.

Acererak the Archlich

When Acererak the Archlich enters, if you haven't completed Tomb of Annihilation, return Acererak the Archlich to its owner's hand and venture into the dungeon.
Whenever Acererak the Archlich attacks, for each opponent, you create a 2/2 black Zombie creature token unless that player sacrifices a creature.