Dark Boo

Dark Boos are purple Boos that appear in Paper Mario: The Thousand-Year Door and Super Paper Mario. They may be found only in the hidden spot of the Poshley Sanctum and also in the Pit of 100 Trials. Dark Boos are more powerful than their white brethren. In Super Paper Mario, they hide in 3-D, waiting for somebody to walk by. Then, they flip to 2-D and attack.

Dark Boos later appeared in Mario & Luigi: Partners in Time in the Gritzy Caves area; it is a faster and stronger type from a counterpart of a Boo. Dark Boos have similar attack movements as Boos. If a Dark Boo opens up its right eye, it means it is going to attack Mario or Baby Mario by appearing behind Mario or Baby and ramming them. If a Dark Boo opens up its left eye, it means it is going to attack Luigi or Baby Luigi by appearing behind Luigi or Baby Luigi and ramming them. Additionally, if one of the Mario Bros. is attacked, the Dark Boo steals either a normal Item or a Bros. Item. The Mario Bros. have to be quick to get those items back because the Dark Boo will run away one turn after stealing the item. They are usualy encountered in large groups, rarely appearing alongside other enemies.