King Boo is the main antagonist and final boss of Luigi's Mansion.
When Professor E. Gadd captured Boolossus, a giant Boo consisting of 15 Boos, word of this reached King Boo. This made him angry, so he led an army of Boos to E. Gadd's lab and released all the portrait ghosts he captured. He then decided to get his revenge on Mario and Luigi, who had caused him and Bowser great trouble in the past. It is hinted that Bowser was destroyed by Mario before the events of this game. King Boo sent a message to Luigi telling him he won a mansion in a contest he didn't even enter. King Boo conjured up this mansion as an illusion, and put all the ghosts, including portrait ghosts, inside it. Mario arrived first, and King Boo imprisoned him in a portrait at the secret altar. He then hid with all the other Boos in the storage room, until Luigi entered and found them. They all escaped him, but he began vacuuming up all the Boos and Portrait Ghosts.
Eventually Luigi reached King Boo at the secret altar. King Boo went into the portrait and sucked Luigi in. In an area resembling the roof of the mansion with a fiery background, King Boo attacked Luigi in a Bowser costume. Luigi thought this was really Bowser until he hit him in the head with a spike bomb, knocking the costume's head off and revealing King Boo, now vulnerable. Finally, Luigi sucked him into the Poltergust along with the Bowser Head, and turned them into a portrait.
King Boo is inside a Bowser suit. He attacks by breathing fire, throwing spike bombs, and jumping high up and coming back down. When he shoots the three spike bombs, Luigi must vacuum them up. To do this, he will have to turn on the vacuum and, with it still activated, move toward the bomb. He must then shoot it at Bowser's head to knock it off. King Boo will come out of the costume and Luigi must use the Poltergust on him to drain his 500 HP. The Bowser head will be floating around shooting ice balls at Luigi that can freeze and severely damage him. To avoid this, Luigi must move around back and forth whenever he fires, while still focusing his attack on King Boo. Eventually he will go back into the Bowser suit and the process must be repeated. Once all his HP is drained, he will be sucked into the Poltergust.
King Boo returned, apparently released from his portrait by Bowser or Bowser Jr., and with a different crown (as Luigi took his previous crown). Mario fought him in Sirena Beach, at the casino. King Boo used a slot machine to send enemies after Mario, but Mario threw a spicy pepper at him, as he dislikes spicy things, and threw food at him to damage him. Once defeated, King Boo exploded.
King Boo sends Boos after Mario, but if Mario sprays him, he will activate his slot machine. Depending on what symbols come up, he will send enemies after Mario, refills for FLUDD, or make food appear. If food appears, Mario must throw a spicy red pepper at King Boo to set his tongue on fire. He must then throw any other kind of fruit (except the dariens, they are hard to pick up and usually can only be kicked) at King Boo to damage him. Three hits will destroy him. Also of note, Mario can stop the ground from spinning by stomping on the purple panels, to make the battle easier.
King Boo returned in Super Princess Peach, this time to fight Princess Peach as the boss of Shriek Mansion, guarding a captive Toad. He is the third boss. He was weak to bright light this time, so Peach had to light all the candles with the Rage vibe. Once defeated, King Boo expanded and exploded again. He has not been seen since.
King Boo attacks by flying at Peach and attempting to fly into her. She must use Rage to light all the unlit candles (there are four candles in the room, two near the ground and two high up). Once all the candles are lit, King Boo will take damage. The process must be repeated four more times, except after three hits, King Boo will start to cry with the Gloom Vibe, which can put out the fire of the torches if he gets near them. The chandelier can be smashed for crystals. After five hits, King Boo will be destroyed.
Super Mario Galaxy 2 Edit
King Boo returned in Super Mario Galaxy 2, this time his boss theme is the same as when fighting Glamdozer.
King Boo charges at Mario slowly, but Mario shone a light on him 3 times.
- Each time King Boo is fought, he is fought by a different character.
- In other versions of Super Mario Sunshine, King Boo is a different character.