Possessor

The Possessors are a group of five ghosts that appear as major bosses of the mansions in Luigi's Mansion: Dark Moon. While each one has their own set of unique abilities, each is capable of possessing another object or being and control them. Unlike other ghosts, Possessors do not have a set HP, instead only being able to be captured by Luigi's Poltergust 5000 once he completes three phases of the boss fight. Each one will drop a shard of the Dark Moon upon being defeated.

Grouchy Possessor
The first Possessor the player encounters is the Grouchy Possessor, found in the Cellar of the Gloomy Manor and can only be fought during the final mission, Confront the Source. It possesses a giant spider and uses its abilities to fight Luigi.

Harsh Possessor
The second Possessor the player fights is the Harsh Possessor, fought in the Tree House of the Haunted Towers. It can only be fought during the final mission, Tree Topping. It possesses a large staircase and sets it aflame to fight Luigi.

Overset Possessor
The third Possessor the player can fight is the Overset Possessor, fought on the Belfry of the Old Clockworks. It is encountered as the boss of the mansion's final mission, Showtime. It possesses a giant clock and uses various abilities and tactics to take on Luigi.

Shrewd Possessor
The fourth Possessor fought is the Shrewd Possessor, encountered in the Workshop of the Secret Mine. While it appears in an earlier mission, it can only be fought during the final mission, Chilly Ride. The Shrewd Possessor possesses the frozen ground beneath Luigi in hopes of escaping with its Dark Moon shard.

Tough Possessor
The fifth and final Possessor to be fought is the Tough Possessor, fought in a different dimension through the paranormal portal during the final mission of the Treacherous Mansion, Stop the Knightmare. This Possessor possesses giant suits of armor in order to fight Luigi, but is able to form trails of electric energy when outside of the armor.