Enemies are among the many obstacles faced by Hector in the Phantom Mansion games, some enemies are unique to a singular Phantom Mansion game.
Zombies are the first enemies ever encountered, the first time they are seen is in the lobby of the Red Chamber, where three zombies are in a room walled off from the player. There is a hidden entrance to the room in the corner. The first time they are seen in a level is in level 3 of the Red Chamber, "Dead Easy". Zombies are blue-skinned with bright green eyes, they wear beige coloured shirts, green trousers and black shoes, they make groaning noises. Zombies only walk in straight lines, when they reach a dead end they will turn back and simply repeat the process. Zombies can push wooden boxes and press switches, however they cannot push metal boxes. If a zombie touches the player, the player will die and fail the level.
Skeletons are the second enemies encountered, the first time they are seen is in level 6 of the Red Chamber, "Heavy Metal". There is a skeleton in the lobby of the Green Gallery, in a small corridor walled off from the player. Skeletons have no eyes, they are white with a blue tint, they make rattling noises. Skeletons only walk in straight lines, when they reach a dead end they will turn back and simply repeat the process. Skeletons can push wooden boxes and press switches, however they cannot push metal boxes. If a skeleton touches the the player, the player will die and fail the level.
Hop-Frog is a jester, first encountered in level 1 of the Indigo Dungeon, "This is Hop-Frog". Hop-Frog moves as the player moves, if Hop-Frog is present in a level, he will steal the player's keys by walking into Hector from the front, he giggles after stealing the player's keys. The goal is to try and trap him in a place where he can no longer move, then touch him from behind, if Hop-Frog is caught then he will not appear again in the level and the player will get their keys back. However, this can sometimes be a daunting task, as Hop-Frog moves in somewhat random patterns that avoid Hector's movements. Hop-Frog can only catch Hector if the player has collected a key, and Hector can only catch Hop-Frog if Hop-Frog has stolen the player's keys. Hop-Frog wears a green and violet checkered outfit with a white collar, a violet jester's hat, black shoes and an indigo mask with bright yellow eyes. Hop-Frog cannot kill the player, so he cannot cause the player to fail the level, however he can make levels much more difficult than they should be. Hop-Frog is a unique aspect of the Indigo Dungeon, he does not appear in any other Phantom Mansion games.
Ghosts are first seen in the final level of the Red Chamber. They are seen in the final level of every Phantom Mansion game, however they are always walled off from the player. The first time they become an actual threat is in the Violet Vault, they first appear in the Violet Vault in level 1, "Keys Open Doors". Ghosts move in a square pattern, they cannot push wooden or metal boxes (or press switches), so their pattern can be altered by positioning boxes. Ghosts make sighing noises and sometimes call out Hector's name, this is probably implying that ghosts are also trapped, just like the souls that Hector is trying to save. Ghosts are white with a violet tint, they have white eyes, a red face and a yellow glow outlining them. If a ghost touches the player, the player will die and fail the level.