See the main article, Uncategorized creatures.

• Some creatures aren't classified as any specific creature type. They have their own properties or differences and therefore can't be placed in a category. Examples include silithid, oozes, some qiraji creatures, and "god" type bosses such as Hakkar the Soulflayer and C'thun.
• A few creatures are unclassified aberrations, such as many hydras, whereas other hydras are considered to be beasts.
• No spells that target a specific type (or types) of creature (such as polymorph and hibernate) work on uncategorized creatures.
• Some can be skinned (e.g. silithids); others (e.g. oozes) cannot.