Cape Feather

Cape Feathers are a type of feather that transforms Mario and Luigi into Cape Mario and Cape Luigi in Super Mario World. As their caped selves, they can hover in the air and fly, similar to the Super Leaf's effect in Super Mario Bros. 3.

The Cape Feather (although referred to as "Feather") was also used in Super Mario Kart for the Super Nintendo as an item a driver could collect from item boxes throughout the race courses. The Feather's effect was the ability to hop roughly double the height the drivers are normally able to, as well as cause them to spin when they do jump. This would be useful for jumping over barriers, as a quick and easy shortcut, and as well as for jumping over enemy projectiles.

The Cape Feather (once more called "Feather") made yet another appearance in Super Mario RPG: Legend of the Seven Stars. Here, it was dropped by Dodo in Nimbus Land's castle, and it gave Mario 20 extra Speed points, 5 more Defense, and 5 more Magic Defense. It was only when this item was equipped that Mario and company could be fast enough to battle Shy Ranger.

Finally, the Cape Feather was also made available as a secret item in Super Mario Advance 4: Super Mario Bros. 3. By scanning in the appropriate card on the e-Reader, the player could upload a Cape Feather into their inventory to use in the game. Cape Mario plays just like he does in Super Mario World, and can even defeat Dry Bones.

Cape Feathers appeared also in Super Mario 64 DS, only Mario was able to use them (except in the multiplayer mode). But instead of giving Mario a cape and gliding/flying abilities, it gave Mario the same powers as a Wing Cap would've given.

Trivia

 * The effects of the Feather in Super Mario Kart are similar to the Roc's Feather's in The Legend of Zelda video game series.
 * The cape feather was inspired by the Super Leaf. Evidence of this is that when a Feather comes out of a block it has a similar motion pattern to the Leaf.