Cordial Vampire

Whenever Cordial Vampire or another creature dies, put a +1/+1 counter on each Vampire you control.

Butcher of Malakir

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

The Ever-Changing 'Dane

{1}, Sacrifice another creature: The Ever-Changing 'Dane becomes a copy of the sacrificed creature, except it has this ability.

Rising Populace

Whenever another creature or planeswalker you control dies, put a +1/+1 counter on Rising Populace.

Kheru Bloodsucker

Whenever a creature you control with toughness 4 or greater dies, each opponent loses 2 life and you gain 2 life.
{2}{B}, Sacrifice another creature: Put a +1/+1 counter on Kheru Bloodsucker.

Galvanic Juggernaut

Galvanic Juggernaut attacks each combat if able.
Galvanic Juggernaut doesn't untap during your untap step.
Whenever another creature dies, untap Galvanic Juggernaut.

Guardian Kirin

Flying
Whenever another creature you control dies, put a +1/+1 counter on Guardian Kirin.

Bane, Lord of Darkness

As long as your life total is less than or equal to half your starting life total, Bane, Lord of Darkness has indestructible.
Whenever another nontoken creature you control dies, target opponent may have you draw a card. If they don't, you may put a creature card with equal or lesser toughness from your hand onto the battlefield.

Sengir, the Dark Baron

Flying
Whenever another creature dies, put two +1/+1 counters on Sengir, the Dark Baron.
Whenever another player loses the game, you gain life equal to that player's life total as the turn began.
Partner (You can have two commanders if both have partner.)

Unruly Mob

Whenever another creature you control dies, put a +1/+1 counter on Unruly Mob.

Elenda, the Dusk Rose

Lifelink
Whenever another creature dies, put a +1/+1 counter on Elenda, the Dusk Rose.
When Elenda dies, create X 1/1 white Vampire creature tokens with lifelink, where X is Elenda's power.

Odric's Outrider

Whenever Odric's Outrider or another creature you control dies, put a +1/+1 counter on target creature you control.

Pitiless Plunderer

Whenever another creature you control dies, create a Treasure token. (It's an artifact with "{T}, Sacrifice this artifact: Add one mana of any color.")