This article/section contains information of a feature that is not confirmed to appear on any game or similar media. This means that the subject of has yet to be confirmed by an official source for the final build for said material.
Boos first appeared in Super Mario Bros. 3. These ghosts froze and covered their face if Mario looked at them, but followed him if he did not. They can only be destroyed if light shines on them (in the Super Mario Galaxy series), if Mario hits them with a Star powerup, or with a Spiny Shell in New Super Mario Bros. for the DS.