Amicus Arcane is a character introduced in the Tales from the Haunted Mansion book series, also credited as the author of the tomes. He is one of the 999 happy haunts that inhabit the Haunted Mansion and serves as the resident librarian.
Very little is actually known about Amicus. His role of librarian was carried over from his life, which implies he was one of the mortal residents of the mansion prior to his afterlife; he remarks in the first volume that President Abraham Lincoln once complimented him on his spats, which if true would mean he lived during the 1860s.
He is an avid reader and lover of all books, but has always had a penchant for horror and ghostly works above all others, and especially enjoys collecting new tales of terror. The biography of John Esposito states that he encountered Amicus while on a midnight walk through New Orleans Square and transcribed the stories, which is why Amicus is credited as the author.
In Volume II, a crypt bearing the surname "Arcane" appears in the Eternal Grace Cemetery, the graveyard adjacent to the Haunted Mansion. This crypt seems to missing its corpse but does have a secret underground passage leading into the mansion, further implying Amicus' lifetime connection with the manor.
Amicus appears as a thin, tall man dressed in an old black suit with a wilted carnation at his lapel. His face is described as being skull-like, with pale and craggy features and wispy white hairs on his head. Rarely is he seen in any environment but the shadowy confines of the library, where often carries a candelabrum for illumination, further emphasizing the gauntness.
Amicus seems to take great delight in being a source of chills, unease and terror, and peppers much of his writing and speech with macabre puns and gallows humor. He is polite and cordial to some extent, often presenting himself as a host or guide to outsiders - so far, he has not shown any truly evil or nefarious tendencies, despite his ghoulish interests. Amicus likewise keeps many secrets, and only offers them when he sees fit.
His mannerisms and tone make him seem very similar to the Ghost Host, and Amicus does introduce himself as a "ghost host" on occasion. However, it is not made clear if they are intended to be the same character.