Cape

The Cape is a magical item first appearing in Super Mario World. Mario and Luigi gain it upon touching a Feather (an item usually found in ? Blocks), and it gives them the ability to fly.

In Super Mario World 2: Yoshi's Island, Baby Mario could get a cape and become invincible by touching a star; Yoshi would turn into a Yoshi Egg.

Mario later uses it as an attack in Super Smash Bros. Melee. While this attack is not particularly powerful, it is useful in that it can reverse the direction of certain projectile attacks.