||Sanae Susaki (2004-present)|
Boos, known in Japan as Teresa (テレサ), are ghosts from the
A Boo's most common pattern of attack is to sneak up on the player (usually Mario) from behind while they are facing away from them; however, they stop their attack if looked at. Being ghosts, they are usually invincible, and unable to be defeated without certain items or conditions.
It has been implied that Boos may have been other living species before they became boos, but this has not been made clear.
 There are also sub-species of Boo based on other species; for example undead
In an interview with
Boos appear as white, spherical, levitating