|Phantom character of Hey Arnold!|
|Voiced by||Steve Viksten|
Four-Eyed Jack is a ghost of a mad scientist who lived at the Sunset Arms many years ago and died because of an accident during an experiment with beans. Now the ghost haunts the boarding house on stormy nights. He appears as a ghost at the end of the episode "Four-Eyed Jack" while awakening Gerald and scaring him before the ghost vanishes in the night. For a ghost however he doesn't seem all too keen on his task of frightening people, he has only ever scared Gerald while retrieving his glasses and quite apathetically at that, "uh, boo".