|Game(s)||Newer Super Mario Bros. DS|
|Appearances||(DS) The House of Stairs|
King Boo attacks you by chasing you through a hallway. There are other boos and spikes in the hallway. King Boo will also shoot ghost balls at you. At the end of the hall way is a switch, press it and it will shrink King Boo to a normal boo size, defeating him.
- King Boo is originally from the Luigi's Manson series.
- His fight is like Boolossus from Newer super Mario bros. Wii, but backwards.
- King Boo is the only boss to not be fought in a tower, castle, or airship, he is fought in a ghost house.
- King Boo is fought in a ghost house, likely a reference to the Mario game "Super Mario World," were the boss big boo is fought in a ghost house.