Phantom

Phantoms are the monsters of Kingdom Hearts Ultima, they are a kind of Unverse like monster that co-operate with Heartless. They manifest from the fear of darkness.

They fight along side Heartless as Phantoms, Heartless and Nobodies are drawn together just as heart body and soul. However whatever creation of these three types of monsters combined is unknown but certainly not human.

Trivia
The name and idea were inspired from ghosts, in which some people fear the darkness for what or who it may hide, even in safe environments like your own bedroom.