From Gamehiker Wiki
|King Boo in the final battle of Luigi's Mansion|
|Eye color||Red or Black|
|Voiced by||Isaac Marshall|
King Boo is not identified by name. He is shown as a Big Boo wearing a crown, and is identified by his laugh (which is the same as his laugh in Luigi's Mansion). King Boo's area is hidden within Big Boo's Haunt, and King Boo must be defeated by Mario in order to free Luigi. In battle King Boo is invisible to Mario, but his reflection is visible in the room's mirror. By observing this, Mario could observe King Boo's movements and attack him. Strangely enough, Luigi appeared as Mario's reflection in the mirror. Mario had to pound King Boo three times to defeat him.
If the game is considered a retcon of Super Mario 64 and takes place before Luigi's Mansion, than this boss battle could be seen as the root of King Boo's grudge with the Mario brothers.
King Boo was the main villain of Luigi's Mansion. In this game, he was shown with red eyes and a ruby crown. King Boo freed the ghosts from Professor E. Gadd's Gallery and then used the combined his powers and with those of his Boo followers to create a fake mansion which looked like it had been around for quite a long time. King Boo then sent a letter to Luigi telling him that he had won the mansion in a contest. King Boo succeeded in capturing Mario when he came to check out the mansion, but he didn't expect Luigi to meet with Professor E. Gadd and use his Poltergust 3000 to suck up the mansion's ghosts until only King Boo remained.
In the final battle, King Boo attacked Luigi on the mansion's rooftop within what appeared to be a giant version of Bowser. But Luigi was able to face his fears and force King Boo out of the Bowser body long enough to suck him into the Poltergust. This caused the mansion to disappear, and King Boo himself was turned into a portrait in E. Gadd's gallery.
King Boo returned in Super Mario Sunshine with a goofier appearance, complete with a sagging tongue and different-colored eyes. He was the boss of Sirena Beach's Hotel Delfino. This time Mario defeated him through a simpler method, by pegging him with fruits.
King Boo also appeared as boss of the Shriek Mansion in Super Princess Peach, where he is formed by a merger of three Boos and guards a captured Toad. He attacked by sending out blue flames, and to defeat him Princess Peach had to light all of the lanterns in the room several times. Every time all of the lights were ignited, King Boo would be damaged and would begin crying more often as he lost more health until he was defeated. His aversion to sunlight in this game is confusing considering that most of his other appearances contradict this.
In Mario Kart DS, King Boo challenges Princess Peach to collect 50 coins over a pit of lava in the Mission 4 Boss Stage, and all the while he tries to steal them back. If he does manage to steal them, all Peach has to do is chase after and jump into him to get them back.
Despite his malevolent nature, King Boo was also playable in several sports games. He was unlockable in Mario Kart: Double Dash!! (where he was unlocked by completing the Star Cup on Mirror Mode, paired with Petey Piranha, rode the Boo Pipes and could use any character's special item) and Mario Kart Wii (where he was unlocked by completing the 50cc Star Cup), as well as being immediately playable in Mario Superstar Baseball and unlockable again in Super Mario Sluggers. In the Challenge Mode of Mario Super Sluggers, he appears in Wario City after Bowser Jr. is defeated there, having watched the battle while invisible out of curiosity to see who was stronger but considered both sides to be "benchwarmers". He would only join the team if the Mini Boo had been found by the team.
King Boo also appeared in Mario Party 8, as the host of the King Boo's Haunted Hideaway board. Like other hosts, King Boo will give stars in exchange for coin payment when they reach his space, but King Boo differs himself from other hosts by hiding himself out of plan sight and then after giving a star to a player he will send all the players back to the starting point of the board by blowing at them.
- He is called Boss Teresa in the Japanese version (Teresa being the Japanese name for Boo).
- In Luigi's Mansion he has 500 HP.