Art by Mike Corker.
Haunted Hill Ghosts are the small ghosts that inhabit the Haunted Hill Zone. The small, almost spherical spirits haunt the interior of the Zone and are said to be very good interrogators, pointing their "fingers" into their target's head and causing them to feel an immense coldness. Some seem to have red eyes that resembles flames although the majority have an orange that almost looks like they're capable of hypnotism.
Nobody knows what the ghosts were before they died. Knuckles the Echidna considered them to be spirits of the soldiers who died during the Great War, although he didn't specify whether they were echidnas or Drakons. All he knew was of their terrifying nature and urged his friends not to get their attention. Buddy, a former Drakon, took this information to mean his former comrades-in-arms now inhabited the Zone and attempted to gain their respect. Unfortunately, the ghosts already had a master - the enormous King Boom Boo. In turn, they also followed Rouge the Bat when she wielded a magic hourglass, although they quickly gave up and went their own way once Rouge had left.
The ghosts are based on the enemies from Sonic Adventure 2 in the "Pumpkin Hill", "Egg Quarters" and "Death Chamber" levels. Different varieties exist, from small ones momentarily popping out from behind graves, slightly larger ones that roam around and attempt to attack intruders and even larger ones that can be brought back down to size with a punch or kick.