|First appearance||Super Mario Galaxy|
Boo Mario is a costume for Mario in Super Mario Galaxy.
On his quest to collect power stars, Mario encounters obstacles he cannot pass normally. He needs special hats to transform and take characteristics of another species, one of which is a Boo.
As A Boo, Mario can fly through the air a short distance, protecting him from hazardous terrain such as quicksand. He can also spin to become intangible and pass through certain walls.
Disturbingly enough, if a real Boo spots Mario, they will develop an attraction to him, and fly toward him, neutralizing the cap if they collide.