Consider

Surveil 1. (Look at the top card of your library. You may put it into your graveyard.)
Draw a card.

Go for the Throat

Stitched Assistant

Exploit (When this creature enters, you may sacrifice a creature.)
When this creature exploits a creature, scry 1, then draw a card. (To scry 1, look at the top card of your library, then you may put that card on the bottom.)

Sidisi, Brood Tyrant

Whenever Sidisi enters or attacks, mill three cards.
Whenever one or more creature cards are put into your graveyard from your library, create a 2/2 black Zombie creature token.

Grixis Slavedriver

When this creature leaves the battlefield, create a 2/2 black Zombie creature token.
Unearth {3}{B} ({3}{B}: Return this card from your graveyard to the battlefield. It gains haste. Exile it at the beginning of the next end step or if it would leave the battlefield. Unearth only as a sorcery.)

Diregraf Scavenger

Deathtouch (Any amount of damage this deals to a creature is enough to destroy it.)
When this creature enters, exile up to one target card from a graveyard. If a creature card was exiled this way, each opponent loses 2 life and you gain 2 life.

Thraben Foulbloods

Delirium — This creature gets +1/+1 and has menace as long as there are four or more card types among cards in your graveyard. (A creature with menace can't be blocked except by two or more creatures.)

Dreg Mangler

Haste
Scavenge {3}{B}{G} ({3}{B}{G}, Exile this card from your graveyard: Put a number of +1/+1 counters equal to this card's power on target creature. Scavenge only as a sorcery.)

Mindleech Ghoul

Exploit (When this creature enters, you may sacrifice a creature.)
When this creature exploits a creature, each opponent exiles a card from their hand.

Agent of the Iron Throne

Commander creatures you own have "Whenever an artifact or creature you control is put into a graveyard from the battlefield, each opponent loses 1 life."

Khenra Eternal

Afflict 1 (Whenever this creature becomes blocked, defending player loses 1 life.)

Hordewing Skaab

Flying
Other Zombies you control have flying.
Whenever one or more Zombies you control deal combat damage to one or more of your opponents, you may draw cards equal to the number of opponents dealt damage this way. If you do, discard that many cards.

Island

Otherworldly Gaze

Surveil 3. (Look at the top three cards of your library, then put any number of them into your graveyard and the rest on top of your library in any order.)
Flashback {1}{U} (You may cast this card from your graveyard for its flashback cost. Then exile it.)

Blood Pact

Target player draws two cards and loses 2 life.

Gleaming Overseer

When this creature enters, 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.)
Zombie tokens you control have hexproof and menace.

Diregraf Horde

When this creature enters, create two 2/2 black Zombie creature tokens with decayed. When you do, exile up to two target cards from graveyards. (A creature with decayed can't block. When it attacks, sacrifice it at end of combat.)

Advanced Stitchwing

Flying
{2}{U}, Discard two cards: Return this card from your graveyard to the battlefield tapped.

Shambling Ghoul

Plague Belcher

Menace
When this creature enters, put two -1/-1 counters on target creature you control.
Whenever another Zombie you control dies, each opponent loses 1 life.

Geralf, the Fleshwright

Whenever you cast a spell during your turn other than your first spell that turn, create a 2/2 blue and black Zombie Rogue creature token.
Whenever a Zombie you control enters, put a +1/+1 counter on it for each other Zombie that entered the battlefield under your control this turn.

Yixlid Jailer

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.

Forest

Unnatural Growth

At the beginning of each combat, double the power and toughness of each creature you control until end of turn.

Josu Vess, Lich Knight

Kicker {5}{B} (You may pay an additional {5}{B} as you cast this spell.)
Menace
When Josu Vess enters, if it was kicked, create eight 2/2 black Zombie Knight creature tokens with menace.

Ghoultree

This spell costs {1} less to cast for each creature card in your graveyard.

Vindictive Lich

When this creature dies, choose one or more. Each mode must target a different player.
• Target opponent sacrifices a creature of their choice.
• Target opponent discards two cards.
• Target opponent loses 5 life.

Patchwork Crawler

{2}{U}: Exile target creature card from your graveyard and put a +1/+1 counter on this creature.
This creature has all activated abilities of all creature cards exiled with it.

Putrid Goblin

Persist (When this creature dies, if it had no -1/-1 counters on it, return it to the battlefield under its owner's control with a -1/-1 counter on it.)

Pontiff of Blight

Extort (Whenever you cast a spell, you may pay {W/B}. If you do, each opponent loses 1 life and you gain that much life.)
Other creatures you control have extort. (If a creature has multiple instances of extort, each triggers separately.)

Arisen Gorgon

This creature has deathtouch as long as you control a Liliana planeswalker. (Any amount of damage this deals to a creature is enough to destroy it.)

Returned Reveler

When this creature dies, each player mills three cards.

Kotis, the Fangkeeper

Indestructible
Whenever Kotis deals combat damage to a player, exile the top X cards of their library, where X is the amount of damage dealt. You may cast any number of spells with mana value X or less from among them without paying their mana costs.

Gisa and Geralf

When Gisa and Geralf enters, mill four cards.
Once during each of your turns, you may cast a Zombie creature spell from your graveyard.

Corpse Augur

When this creature dies, you draw X cards and you lose X life, where X is the number of creature cards in target player's graveyard.

Quest for the Gravelord

Whenever a creature dies, you may put a quest counter on this enchantment.
Remove three quest counters from this enchantment and sacrifice it: Create a 5/5 black Zombie Giant creature token.

Catapult Captain

{2}{B}, {T}, Sacrifice another creature: Target opponent loses life equal to the sacrificed creature's toughness.

Catapult Fodder

At the beginning of combat on your turn, if you control three or more creatures that each have toughness greater than their power, transform this creature.

Catapult Fodder // Catapult Captain

Marauding Boneslasher

This creature can't block unless you control another Zombie.

Dismal Backwater

This land enters tapped.
When this land enters, you gain 1 life.
{T}: Add {U} or {B}.

Tergrid's Shadow

Each player sacrifices two creatures.
Foretell {2}{B}{B} (During your turn, you may pay {2} and exile this card from your hand face down. Cast it on a later turn for its foretell cost.)

Refurbished Familiar

Affinity for artifacts (This spell costs {1} less to cast for each artifact you control.)
Flying
When this creature enters, each opponent discards a card. For each opponent who can't, you draw a card.

Grizzly Ghoul

Trample
This creature enters with a +1/+1 counter on it for each creature that died this turn.

Rank Officer

When this creature enters, you may discard a card. If you do, create a 2/2 black Zombie creature token.
{1}{B}, {T}, Exile a creature card from your graveyard: Each opponent loses 2 life.

Tomebound Lich

Deathtouch (Any amount of damage this deals to a creature is enough to destroy it.)
Lifelink (Damage dealt by this creature also causes you to gain that much life.)
Whenever this creature enters or deals combat damage to a player, draw a card, then discard a card.

Skaab Ruinator

As an additional cost to cast this spell, exile three creature cards from your graveyard.
Flying
You may cast this card from your graveyard.

Gravedigger

When this creature enters, you may return target creature card from your graveyard to your hand.

Liliana, Death Mage

+1: Return up to one target creature card from your graveyard to your hand.
−3: Destroy target creature. Its controller loses 2 life.
−7: Target opponent loses 2 life for each creature card in their graveyard.

Rakshasa's Bargain

Look at the top four cards of your library. Put two of them into your hand and the rest into your graveyard.

Unbreathing Horde

This creature enters with a +1/+1 counter on it for each other Zombie you control and each Zombie card in your graveyard.
If this creature would be dealt damage, prevent that damage and remove a +1/+1 counter from it.

Molderhulk

Undergrowth — This spell costs {1} less to cast for each creature card in your graveyard.
When this creature enters, return target land card from your graveyard to the battlefield.

Eaten Alive

As an additional cost to cast this spell, sacrifice a creature or pay {3}{B}.
Exile target creature or planeswalker.

Drownyard Amalgam

When this creature enters, target player mills three cards. (They put the top three cards of their library into their graveyard.)
{2}{U}: This creature can't be blocked this turn.

Aven Eternal

Flying
When this creature enters, 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.)

Unclaimed Territory

As this land enters, choose a creature type.
{T}: Add {C}.
{T}: Add one mana of any color. Spend this mana only to cast a creature spell of the chosen type.

Woodland Cemetery

This land enters tapped unless you control a Swamp or a Forest.
{T}: Add {B} or {G}.

Shriekdiver

Flying
{1}: This creature gains haste until end of turn.

Wretched Camel

When this creature dies, if you control a Desert or there is a Desert card in your graveyard, target player discards a card.

Lie in Wait

Return target creature card from your graveyard to your hand. Lie in Wait deals damage equal to that card's power to target creature.

Rooftop Storm

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

Rictus Robber

When this creature enters, if a creature died this turn, create a 2/2 blue and black Zombie Rogue creature token.
Plot {2}{B} (You may pay {2}{B} and exile this card from your hand. Cast it as a sorcery on a later turn without paying its mana cost. Plot only as a sorcery.)

Walking Sarcophagus

Start your engines! (If you have no speed, it starts at 1. It increases once on each of your turns when an opponent loses life. Max speed is 4.)
Max speed — This creature gets +1/+2.

Death Begets Life

Destroy all creatures and enchantments. Draw a card for each permanent destroyed this way.

Cellar Door

{3}, {T}: Target player puts the bottom card of their library into their graveyard. If it's a creature card, you create a 2/2 black Zombie creature token.

Farbog Boneflinger

When this creature enters, target creature gets -2/-2 until end of turn.

Moldering Karok

Undead Gladiator

{1}{B}, Discard a card: Return this card from your graveyard to your hand. Activate only during your upkeep.
Cycling {1}{B} ({1}{B}, Discard this card: Draw a card.)

Rhet-Tomb Mystic

Flying
Each creature card in your hand has cycling {1}{U}. ({1}{U}, Discard that card: Draw a card.)

Champion of the Perished

Whenever another Zombie you control enters, put a +1/+1 counter on this creature.

Contaminated Aquifer

({T}: Add {U} or {B}.)
This land enters tapped.

Infectious Horror

Whenever this creature attacks, each opponent loses 2 life.

Choked Estuary

As this land enters, you may reveal an Island or Swamp card from your hand. If you don't, this land enters tapped.
{T}: Add {U} or {B}.

Grimgrin, Corpse-Born

Grimgrin enters 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.

Cryptcaller Chariot

Menace
Whenever you discard one or more cards, create that many tapped 2/2 black Zombie creature tokens.
Crew 2

Silversmote Ghoul

At the beginning of your end step, if you gained 3 or more life this turn, return this card from your graveyard to the battlefield tapped.
{1}{B}, Sacrifice this creature: Draw a card.

Open the Graves

Whenever a nontoken creature you control dies, create a 2/2 black Zombie creature token.

Liliana of the Veil

+1: Each player discards a card.
−2: Target player sacrifices a creature.
−6: Separate all permanents target player controls into two piles. That player sacrifices all permanents in the pile of their choice.

Myriad Landscape

This land enters tapped.
{T}: Add {C}.
{2}, {T}, Sacrifice this land: Search your library for up to two basic land cards that share a land type, put them onto the battlefield tapped, then shuffle.

Flip the Switch

Counter target spell unless its controller pays {4}. Create a 2/2 black Zombie creature token with decayed. (It can't block. When it attacks, sacrifice it at end of combat.)

Deathless Pilot

This creature saddles Mounts and crews Vehicles as though its power were 2 greater.
{3}{B}: Return this card from your graveyard to your hand.

Rot Hulk

Menace
When this creature enters, return up to X target Zombie cards from your graveyard to the battlefield, where X is the number of opponents you have.

Coffin Queen

You may choose not to untap this creature during your untap step.
{2}{B}, {T}: Put target creature card from a graveyard onto the battlefield under your control. When this creature becomes untapped or you lose control of this creature, exile that creature.

Farseek

Search your library for a Plains, Island, Swamp, or Mountain card, put it onto the battlefield tapped, then shuffle.

Persistent Constrictor

At the beginning of each opponent's upkeep, they lose 1 life and you put a -1/-1 counter on up to one target creature they control.
Persist (When this creature dies, if it had no -1/-1 counters on it, return it to the battlefield under its owner's control with a -1/-1 counter on it.)

Diregraf Captain

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

Eater of Hope

Flying
{B}, Sacrifice another creature: Regenerate this creature.
{2}{B}, Sacrifice two other creatures: Destroy target creature.

Falcon Abomination

Flying
When this creature enters, create a 2/2 black Zombie creature token with decayed. (It can't block. When it attacks, sacrifice it at end of combat.)

Bushwhack

Choose one —
• Search your library for a basic land card, reveal it, put it into your hand, then shuffle.
• Target creature you control fights target creature you don't control. (Each deals damage equal to its power to the other.)

Archghoul of Thraben

Whenever this creature 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.

Dryad's Revival

Return target card from your graveyard to your hand.
Flashback {4}{G} (You may cast this card from your graveyard for its flashback cost. Then exile it.)

Lazotep Chancellor

Whenever you discard a card, you may pay {1}. If you do, 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.)

Liliana's Triumph

Each opponent sacrifices a creature of their choice. If you control a Liliana planeswalker, each opponent also discards a card.

Vile Entomber

Deathtouch (Any amount of damage this deals to a creature is enough to destroy it.)
When this creature enters, search your library for a card, put that card into your graveyard, then shuffle.

Butcher of Malakir

Flying
Whenever this creature or another creature you control dies, each opponent sacrifices a creature of their choice.

Liliana of the Dark Realms

+1: Search your library for a Swamp card, reveal it, put it into your hand, then shuffle.
−3: Target creature gets +X/+X or -X/-X until end of turn, where X is the number of Swamps you control.
−6: You get an emblem with "Swamps you control have '{T}: Add {B}{B}{B}{B}.'"

Silumgar Scavenger

Flying
Exploit (When this creature enters, you may sacrifice a creature.)
Whenever another creature you control dies, put a +1/+1 counter on this creature. It gains haste until end of turn if it exploited that creature.

Priest of the Haunted Edge

{T}, Sacrifice this creature: Target creature gets -X/-X until end of turn, where X is the number of snow lands you control. Activate only as a sorcery.

Slitherhead

Scavenge {0} ({0}, Exile this card from your graveyard: Put a number of +1/+1 counters equal to this card's power on target creature. Scavenge only as a sorcery.)

Zombie Ogre

At the beginning of your end step, if a creature died this turn, venture into the dungeon. (Enter the first room or advance to the next room.)

Unshakable Tail

When this creature enters and at the beginning of your upkeep, surveil 1.
Whenever one or more creature cards are put into your graveyard from your library, investigate. (Create a Clue token. It's an artifact with "{2}, Sacrifice this token: Draw a card.")
{2}, Sacrifice a Clue: Return this card from your graveyard to your hand.

Fell Stinger

Deathtouch
Exploit (When this creature enters, you may sacrifice a creature.)
When this creature exploits a creature, target player draws two cards and loses 2 life.

Gravecrawler

This creature can't block.
You may cast this card from your graveyard as long as you control a Zombie.