The Catalysts are a special variant of zombie with elemental powers that appear in Call of Duty: Black Ops 4 Zombie mode on Voyage of Despair, IX, Dead of the Night, and Ancient Evil. Within Voyage of Despair each respective type of Catalyst can drop a part for the Distillery Sill allowing the Kraken to fire the respective element distilled.
Catalysts will first start appearing around round 8. They spawn from regular zombies, melting the flesh of the common undead enemy, and revealing the Catalyst inside. Catalysts have 4 different elemental variants.
- Fire - Fire Catalysts are very similar to Napalm Zombies. They move very slowly and will explode when killed or when they get within melee range of a player. The explosion knocks down other enemies, giving the player an advantage of killing the others when they're not attacking.
- Water - Water Catalysts are the least aggressive of the Catalysts, preferring to stay away from players and roam. They are constantly in a hunched over position and glow bright blue. They buff regular zombies, making them both deal more damage and become more resilient to damage which is indicated by a blue aura around that zombies head. When the round nears its end, Water Catalysts tend to get more aggressive.
- Poison - Poison Catalysts glow green and have a notable green aura that surrounds them. They deal poison damage by being near players but will rarely attack directly.
- Lightning - Lightning Catalysts glow bright yellow and hold their heads. They have the farthest range of any Catalyst. When they spot a player they will attack by screaming which will blind and deafen anyone it hits, similar to Shrieker Zombies. The blindness only persists while the Catalyst is screaming and both vision and hearing will return as soon as it is killed or stops screaming.