Oareos are a personal enemy created by Iago Koopa. They will only listen to Iago and will always do what he tells them to do. They first appeared in Mario Party, where they appear in several minigames. They first appear in New Super Mario Bros.
Oareos have a spike on top of their head. They constantly switch between poking it out and hiding it inside their head. When they are hiding the spike, they can be defeated by jumping on their head. They take two hits to be defeated.