"This possessor was hiding at the top of that giant tree in the Haunted Towe'rs. He possessed a wooden staircase, of all things, and tried to eat Luigi! I thought he was going to faint!"—E. Gadd's Ghost Container, Luigi's Mansion: Dark Moon
As the others Possessors, this is a white ghost with two horns protruding from the front of its head. In the battle, he possess the staircase of the Tree House; to defeat the Harsh Possessor, Luigi must wait for him to fly into the air and attempt to crush him. If the Possessor misses, the staircase will fall, become flat, and reveal its "tongue"; now, Luigi must use his Poltergust 5000 to stretch the tongue and send it flying back into the staircase to make the Harsh Possessor fly out. After the Harsh Possessor shows its true self, Luigi can use the Strobulb to stunned him and removing his skins, as the other Possessors.