Citizen Zombie

Combustible Corpse. Any fire damage has a chance to ignite the Zombie and cause instant death. Zombie rolls a dc 15 save against fire damage to not ignite and die.

Holy Redemption. If radiant damage is dealt, or if a revivify, resurrection, true resurrection spell is cast on the zombie it has a chance of instant death. Zombie rolls a dc 18 save.

Go For The Head. Only on natural DC20 using a slashing or piercing attack can creatures sever the zombies head to kill it. Unless the creatures make a one time history check DC16 to determine if they know to cut off the head. Creatures may make an investigation check DC(5-18 depending on the DM and the situation)  on their turns to determine if they figured out to go for the head. If they know to go for the head they may make regular attack rolls against the zombies AC of 5 with a penalty of -8 to hit. If they hit with slashing or piercing damage the zombie is killed instantly.

Easy Prey. The zombie has a +10 to hit with any attacks against a target it is grappling.

Zombie Infection. Any target that takes any amount of damage from the zombie is Infected pending a constitution check DC19. An infected target will die in twenty-four hours and become a zombie. The only way to cure this is with a Greater Restoration spell, or a Holy Redemption Potion. Infected must be cured before they die or will become zombies.

Scratch. Melee Weapon Attack: -5(+5 if the target is grappled) to hit, reach 5 ft, one target. Hit: 4 (1d4 + 1) Slashing damage.

Bite. Melee Weapon Attack: +10 to hit, Target must be grappled, one target, Hit: 22 (4d8 + 6) Slashing damage.

Grapple. The target must be no more than large size and must be within 5ft. Using at least one free hand, the zombie tries seize the target by making a grapple check instead of an attack roll: a Strength (Athletics) check contested by the target's Strength (Athletics) or Dexterity (Acrobatics) check (the target chooses the ability to use). The zombie succeeds automatically if the target is incapacitated. If the zombie succeeds the target is under the grappled condition. The condition specifies the things that end it, and the zombie can release the target whenever it wants (no action required).