Hoot

Hoot is an owl that appears in Whomp's Fortress in Super Mario 64. They appear when the player climbs a certain tree in the beginning segment of Whomp's Fortress, and can be grabbed in order to fly around the level. Hoot is required in order to obtain a star.

Wing Cap Replacement
In some personalized copies of Super Mario 64, a Wing Cap appears in place of Hoot. This makes it harder to obtain the star that requires Hoot to reach.

Pink Box
In some personalized copies of Super Mario 64, upon finding Hoot, pink boxes can appear that contain Hoot when broken. These can usually only appear in Whomp's Fortress, though has been reported in other levels.