Devil Watcher

A Devil Watcher is a creature that, according to Knuckles, appeared in Mobian fairy tales.

History
Knuckles encountered one Devil Watcher on his way through a remote section of the Great Forest on his quest to find the King's Sword of Acorns, causing him to remark upon its status as a creature of myth, before causing a tree to fall onto it. This caused it to apparently "die", dissolving into a grayish mist.

Merlin Prower later revealed that the Watcher had been summoned by himself as one of the ways he protects himself as a charlatan.