Any beast, dragon, giant, humanoid, or monstrosity can be raised as a zombie . A zombified creature retains all its stats except as noted below.

Type. The zombie’s type is undead. It does not require air, sustenance, or sleep.

Ability Scores. The zombie’s ability scores are reduced to the following, unless they’re already lower: Dex 6 (–2), Int 3 (–4), Wis 8 (–1), Cha 4 (–3).

Saving Throws. The zombie loses all saving throw proficiencies.

Speed. Any speed the creature has is reduced by 10, or to 30, whichever is lower.

Skills. The zombie loses all skill proficiencies.

Immunities. The zombie gains immunity to poison damage, fatigue, and the poisoned condition.

Senses. The zombie gains darkvision out to a distance of 60 feet.

Languages. The zombie understands the languages it knew in life but can’t speak or take any action requiring vocalization.

Traits. The zombie loses all traits, but gains Undead Fortitude.

Actions and Abilities. The zombie loses all spellcasting abilities and any actions that create magical effects.

Actions. The zombie can gain the grab and bite attacks of the zombie if the base creature has the capability to grab and bite. If the creature has Multiattack, it can replace weapon attacks in its multiattack with a grab or bite. Both attacks use Strength for attack and damage rolls. The grab deals 1d6 bludgeoning damage plus 1d6 for each size category above Medium. The bite deals 1d10 piercing damage plus 1d10 for each size category above Medium. The escape DC for the zombie’s grab is equal to its maneuver DC. It loses any ranged attacks that require the use of a weapon more complex than a  rock. It also loses any legendary actions and bonus actions.

You can treat a group of 5 to 10 identical NPCs or other monsters as a single creature by applying the Squad template to the base creature’s stat block. This allows high-level characters to battle large numbers of enemies without bogging down the game in dozens of die rolls each turn.

The squad template is best used on intelligent, organized creatures with a Challenge Rating 3 or lower that are size Small or larger. Creatures with short, simple stat blocks make the best squads. Depending on the nature and organization of the creatures, the squad may be called a unit, squad, or horde of creatures.

A squad retains all the statistics of one of its members except as noted below.

Size. The squad’s Size increases by two categories. If the base creature is Small, the squad’s Size instead increases to Large.

Type. The squad’s new type is “group of [the original creature’s size and type].”

Challenge Rating. You can recalculate the squad’s CR using the information in Appendix C: Designing Monsters, or you can use the following shortcut: new CR = (old CR x 4) + 2, rounded up. An altered Challenge Rating may cause the squad’s Proficiency Bonus to change as well.

HP. The squad’s hit points, bloodied hit points, and number of hit dice are multiplied by 5.

The squad gains the following traits:

Area Vulnerability. The squad takes double damage from any effect that targets an area.

Squad Dispersal. When the squad is reduced to 0 hit points, it turns into 2 (1d4) base creatures, each of which are bloodied .

Squad. The squad is composed of 5 or more creatures. If it is subjected to a spell, attack, or other effect that affects only one target, it takes any damage but ignores other effects. It can share its space with Medium or smaller creatures or objects. The squad can move through any opening large enough for one base creature without squeezing.

Damage and Healing. Any action or trait that deals damage deals five times the usual damage, or half that if the squad is bloodied . Any action or trait that restores hit points restores five times the usual hit points, or half that if the squad is bloodied.

Any beast, giant, humanoid, or monstrosity that has bones can be animated as a skeleton. A skeletal creature retains all its statistics except as noted below.

Type. The skeleton’s type is undead. It does not require air, sustenance, or sleep.

Ability Scores. The skeleton’s mental ability scores are reduced to the following scores (unless they are already lower): Int 6 (–2), Wis 8 (–1), Cha 5 (–3).

Skills. The skeleton loses all skills.

Vulnerability. The skeleton gains vulnerability to bludgeoning damage.

Immunities. The skeleton gains immunity to poison damage and to fatigue and the poisoned condition.

Senses. The skeleton gains darkvision out to a distance of 60 feet.

Languages. The skeleton understands the languages it knew in life but can’t speak. It can’t take any action that requires speech or vocalization.

Traits. The skeleton loses all traits.

Magical Abilities. The skeleton loses all spellcasting abilities and any actions that create magical effects.

Any NPC can be a sahuagin. A sahuagin NPC retains all its statistics except as noted below.

Speed. The sahuagin gains a swim speed of 40 feet.

Senses. The sahuagin gains darkvision with a radius of 120 feet.

Languages. The sahuagin speaks Sahuagin.

Blood Frenzy. The sahuagin has advantage on melee attack rolls against creatures that don’t have all their hit points.

Limited Amphibiousness. The sahuagin can breathe air and water. When breathing air, it must immerse itself in water once every 4 hours or begin to suffocate .

Shark Telepathy. The sahuagin can command any shark within 120 feet of it using magical telepathy.

The sahuagin has the following additional action:

Claw. Melee Weapon Attack: proficiency bonus plus Strength bonus to hit, reach 5 ft., one target. Hit: 1d8 + Strength bonus slashing damage.

The sahuagin has the following additional bonus action:

Bite. Melee Weapon Attack: proficiency bonus plus Strength bonus to hit, reach 5 ft., one target. Hit: 1d4 + Strength bonus piercing damage.

Any NPC can be a merfolk. A merfolk NPC retains all its statistics except as noted below.

Speed. The merfolk has a Speed of 10 feet and a swim speed of 40 feet.

Senses. The merfolk gains darkvision with a radius of 30 feet.

Languages. The merfolk speaks Aquan and Common.

Amphibious. The merfolk can breathe air and water.

If the merfolk’s Challenge Rating is 2 or higher and it is wielding a trident, it can take the following additional bonus action:

Trident. The merfolk makes a trident attack.