Mr Gool is apparently a human man.
Description[]
Mr Gool is a man who inhabits the Haunted Mansion, and claims to be its current mortal owner, apparently having inherited it (through some family relationship with the Tightrope Girl, per Minnie Mouse's reckoning). He is the husband of Madame Leota, a fact which would suggest he either married her postmortem, or that he is himself more supernatural in nature than he lets on.
One Halloween night, Mr Gool invited the Squeaky Cleaners (a group consisting of Mickey Mouse, Minnie Mouse, Donald Duck, Goofy, Daisy Duck, and Pluto) to clean the Haunted Mansion, omitting the fact that the mansion was, in fact, haunted. The group soon discovered the fact on their own, after becoming lost in the Mansion's maze of corridors and running into quite a few unmistakable spooks.
Behind the scenes[]
Mr Gool first appeared in the book The Haunted Mansion: Haunted Happenings.
It is possible he is meant to be a physical form of the Ghost Host, as the Host doesn't otherwise appear in the book and Gool takes on his narrative role. However, Gool is neither invisible, nor physically similar to the Ghost Host's canonical self.