Ghost (Super Mario Galaxy 2)

Ghosts are helpful characters that appears in the Wii game Super Mario Galaxy 2. They can be found at the start of the all galaxies, at a point of the game. They are useful to show where the Comet Medals or some hidden Stars. When the mission begins, the Ghost will be in a kind of athlete-running in the same place. To activate it, Mario/Luigi should be close of the it. Once activated, will run, passing by shortcuts to reach a Comet Medal or Power Star, finding this objects, it will sleep. While running, the ghost will leave a green arrow trail.

Strangely, the ghost resembles Luigi.