Octoboo

Octoboos are ghostly Octoombas that appear in Super Mario Galaxy 2. They primarily move around by floating in a set area. Octoboos cannot be defeated; they become transparent when the player uses a spin near them or from Yoshi's tongue. Octoboos also make small Octoomba sounds if Mario or Luigi is close to them. Unlike most members of the Octoomba family, they do not spit rocks.

Octoboos appear in Haunty Halls Galaxy, Boo Moon Galaxy, and Flash Black Galaxy as regular enemies. In A Glimmer of Bulb Berry, they are the first enemies to be encountered. They can be found in groups while encircling a select area, behaving somewhat like Circling Boo Buddies or Peepas in later games. In Haunting the Howling Tower, Boo Mario has to avoid these enemies to progress through the area.