Revenant

Revenant CR: 5

Medium undead, neutral

Armor Class: 13 (leather armour)

Hit Points: 136 16d8+64

Speed: 30 ft

STR

18 +4

DEX

14 +2

CON

18 +4

INT

13 +1

WIS

16 +3

CHA

18 +4

Saving Throws: Str +7, Con +7, Wis +6, Cha +7

Damage Resistances: Necrotic, Psychic

Damage Immunities: Poison

Condition Immunities: Charmed, Exhaustion, Frightened, Paralyzed, Poisoned, Stunned

Senses: Darkvision 60 ft, passive Perception 13

Languages: The languages it knew in life

Challenge Rating: 5

Regeneration. The revenant regains 10 hit points at the start of it's turn. If the revenant takes fire or radiant damage, this trait doesn't function at the start of the revenant's next turn. The revenant's body is destroyed only if it starts it's turn with 0 hit points and doesn't regenerate.
Rejuvenation. When the revenant's body is destroyed, it's soul lingers. After 24 hours, the soul inhabits and animates another humanoid corpse on the same plane of existence and regains all of it's hit points. While the soul is bodiless, a Wish spell can be used to force the soul to go to the afterlife and not return.
Turn Immunity. The revenant is immune to effects that turn undead.
Vengeful Tracker. The revenant knows the distance to and direction of any creature against which it seeks revenge, even if the creature and the revenant are on different planes of existence. If the creature being tracked by the revenant dies, the revenant knows.
Variant: Revenants with spells and weapons. Revenants that were spellcasters before they died might retain some or all of their spellcasting abilities. Similarly, revenants that wore armour and wielded weapons in life might continue to do so.

Actions

Multiattack. The revenant makes two fist attacks.
Fist. Melee Weapon Attack +7 to hit, reach 5 ft, one target. Hit 11 2d6+4 bludgeoning damage. If the creature is a creature against which the revenant has sworn vengeance, the target takes an extra 14 4d6 bludgeoning damage. Instead of dealing damage, the revenant can grapple the target (escape DC 14), provided the target is Large or smaller.
Vengeful Glare. The revenant targets one creature it can see within 10 feet of it and against which it has sworn vengeance. The target must make a DC 15 Wisdom saving throw. On a failure, the target is paralyzed until the revenant deals damage to it, or until the end of he revenant's next turn. When the paralysis ends, the target is frightened of the revenant for 1 minute. The frightened target can repeat can repeat the saving throw at the end of each of it's turns, with disadvantage if it can see the revenant, ending the frightened condition on itself on a success.

Revenants are the living dead. They return to life to right some wrong, or to spread disorder & chaos. The former is the most common. Found primarily in Western Europe, other creatures, such as vampires are sometimes lumped into this group.
A revenant has one year to track down and cause the destruction of whoever wronged him or her, and can inhabit the corpse of another if it's own is destroyed. A person who is being hunted can always identify the revenant in any form it has. The revenant has it's intelligence and mind largely intact during this time. If it doesn't succeed, the body crumbles and the soul enters the afterlife.
It always knows the direction of it's intended victim or victims, and if they are still alive. If destroyed itself during this time before the year is up or not finished then it's spirit flies out into the nearest body. A revenant is hunting this creature or creatures if it was killed when innocent or unnecessarily. Whether stabbed in the back, hung for a crime it didn't commit, or some other type of death, there is always a risk a revenant will return.
As the revenant is undead, it doesn't need to eat, drink, sleep or need air.

Suggested Environments

Any.