These are all default registry entries of this type.
This registry is modify-able through datapacks.
npc
mob
minecraft:polar_bear
other
mmorpg:water_mage
mmorpg:healer_mage
mmorpg:fire_mage
minecraft:zombified_piglin
minecraft:iron_golem
minecraft:ender_dragon
minecraft:enderman
minecraft:zombie
minecraft:drowned
animal
minecraft:wolf
lycanite_mobs
minecraft:wither
mmorpg:nature_mage
minecraft:bee
player