King Boo

"I am not afraid of you, fool! I fear only that infernal Poltergust 3000 you carry on your back! Stupid machine! But I am a KING among Boos! I swear it... I shall fear no mere house-cleaning device!!"

- King Boo prepares for the final battle in Luigi's Mansion. "Mwah ha ha! Now what do we have here? Why, if it isn't my old pal Luigi! Or is it Baby Luigi? I can't tell the difference. Hey, remember that time you trapped me in a painting for all eternity? Good times. But guess what? I GOT OUT! And now I'm painting the town RED!"

- King Boo shows up for the final battle in Luigi's Mansion: Dark Moon.

King Boo is the main antagonist of the Luigi's Mansion trilogy and is a recurring character in the Mario games, who appears under different shapes and roles most commonly as a boss character. He made his debut in the first Luigi's Mansion game.

As his name suggests, he is the king of the entire Boo race. He is considered to be Luigi's nemesis as Bowser is to Mario. Despite having the same name and role, the King Boo from the main games seems to act differently from his first appearance in the Luigi's Mansion spinoff.

He also appears as a playable character in Mario Super Sluggers, Mario Kart Wii (in which he can be unlocked by winning the 50cc Star Cup or by playing 750 races in which he is very easy to unlock), Mario Kart 8 Deluxe and Mario Kart Tour.

He was voiced by Toru Asakawa, who also voices Dry Bones in the Mario games starting with Mario Party 7.

Appearance
In the Luigi's Mansion series, King Boo appears as a large Boo with magenta eyes, an indigo tongue, and grey colored body that is sometimes shrouded in shadows. He also wears a crown that has a large magenta jewel embedded on top of it. In the first Luigi's Mansion game, his eyes and crown jewel were originally colored red.

In various other Mario games, King Boo resembles other Boos, albeit larger and wears a smaller crown that has tiny red and blue jewels on the rim instead of a large one on the top.

Besides possessing the abilities of other Boos, including the ability to teleport, King Boo has a number of other magical powers. Notably, it should be mentioned that King Boo's power increases when he is in the presence of other Boos. King Boo also has the incredible power to materialize things out of thin air. He has also shown the ability to create Boos, bubbles, and blue fire, which he spits out of his mouth.

Although King Boo is a lot larger than regular Boos, he is not the largest of the Boos. However, even gigantic Boos like Boolossus follow his leadership, despite their superior size. This is likely because he is the most intelligent and the most powerful of the Boos. King Boo seems to have a passion for gambling, as the entrance to each wing in Luigi's Mansion was modeled after a playing card suit (spade, club, heart, and diamond), he is fought atop a slot machine in a casino in Super Mario Sunshine, and (though this is non-canon), his Rival match in Mario & Sonic at the London 2012 Olympics Games is at Bingo Highway, a casino-themed stage from Sonic Heroes.

King Boo also has an extreme dislike for the Mario Bros., due to their constant intervention in the plans of the Boo leader and others of his kind, especially towards Luigi. He shows a bit of a snarky side in Dark Moon when he confronts Luigi with "Remember when you trapped me for all eternity in a painting? Good times." Lastly, King Boo has a distinct cackle, which is significantly lower in pitch than other Boos.

King Boo hates spicy things, as throwing a jalapeno pepper in his mouth will set his tongue on fire and make him vulnerable.

Personality
King Boo is notably darker in Luigi's Mansion than in other games. King Boo initially was much fairer in his rule, going out of his way to save a high-ranking Boo and generally acting fond of his own troops. He despised the Mario Brothers, and so plotted to get rid of them by capturing Mario and then tricking Luigi, so he could store them both into paintings. He also hates Professor E. Gadd for similar reasons, his Poltergust the only thing he fears.

In the sequel, all King Boo's altruistic traits have been rendered null. King Boo, after his first defeat, started to loathe Luigi even more than E. Gadd and Mario, to the point of conducting an elaborate revenge scheme involving shattering the Dark Moon and causing the benevolent ghosts to fly out of control. King Boo is consumed by revenge and notably cares little for his troops, experimenting on the ghosts he enslaved and broke into submission and treating his Boos as common casualties. It reaches the point where King Boo willingly opens a portal to the ghost's homeworld with the intent to destroy the universe as an act of spite. King Boo is noticeably less comedic and more openly cruel to Luigi, as well as sadistic, clearly relishing the terrified Luigi's pain with his mind games.

In Luigi's Mansion 3, King Boo seems to be even more determined to achieve his vengeance, sadistically taunting Luigi over the capture of his friends and family while becoming visibly infuriated by his forces' inability to stop him. Despite being freed by her, he shows no affection for Hellen Gravelly or her efforts to impress him, openly stating that he wasn't confident that her plan would work when confronting Luigi, refusing to give her the opportunity to make up for her shortcoming and later disregarding her entirely for her failure. He eventually becomes fed up with relying on other ghosts to do his dirty work, deeming them all as useless, and instead decides to forego carefully laid out plans and traps in favor of tackling his enemies directly. During the final battle, he focuses himself entirely on removing his opposition to the point where he is willing to trap The Last Resort and everything around it inside a painting simply to get rid of Luigi. He further shows how much he hates him by attacking him right away despite Mario and Peach being there. Overall, this version of King Boo is a purely evil spirit who disregarded any care he had concerning his subjects. He is one of the evilest villains in the series by far.

Theories
Many fans speculated due to Bowser Robot that King Boo used in his first battle against Luigi, as compared to the other mechs in the Mario universe, this one looks quite realistic. As the Mario universe has no set timeline, fans say that it is possible for Bowser to get killed and King Boo inhabiting his corpse. As the last game before King's debut was Paper Mario set in Japan as Mario Story, people say that one of the ghosts in the first mansion is reading Mario Story, which can be a historical book. Also, fortune-teller in the mansion exclaimed that King Boo could possibly revive Bowser, which means that King Koopa was already dead. There are several visions of the situation:


 * King Boo revives Bowser and takes his place as Koopa King, so in future games, Bowser gains supernatural abilities to stay alive even when burned to the bones like in New Super Mario Bros. with his Dry Bowser form. Then, King Boo which we see is actually just a Big Boo with a fancy crown, imitating King Boo. This can be canon due to the blue supernatural fire of Bowser, his Dry Bowser form (which also explains that regular Boos inhabit Dry Bones and are confused, when the player beats them only for Boos to return into skeletons), and the gold portrait of King Boo, showing him and Bowser having a confrontation.


 * King Boo revives Bowser and they make an alliance against Mario Bros, so King Boo is able to revive Bowser anytime when he gets killed and takes his body until Bowser recovers. This version means that King Boo looks like a regular Big Boo because of the loss of his enchanted power-crown, which gives him incredible battle powers and creepy look. This can be canon due to the pose of Bowser in the portrait, like having sleep before King Boo inhabits him, and also a gold portrait of King Boo, showing his confrontation with Bowser.


 * King Boo and Bowser are one and the same person. After his death, Bowser turns into a ghost, namely Boo, but still has some of his magic powers, which allowed him to bow Boos to his will. Then, he recreates his body (or creates a very similar mech) to inhabit it. However, he was unable to fully recover, so he traps Mario, though fails in capturing Luigi. This theory provides a thought of Boo-Regent like the one in the first variant. This can be canon due to Bowser having a good relationship with Boo and also quote of King Boo of Mario "giving him many troubles in the past". Also, this can be considered canon, as Bowser still has powers to be revived, as it is done not only by himself, but by Bowser Jr., Koopalings, and Kamek on several occasions.


 * That the Bowser fought in Luigi's Mansion is actually a powerful illusion created by King Boo. In Luigi's Mansion: Dark Moon, Boos are seen sealing Toads inside portraits and using "Spirit Balls" to make objects invisible. These paranormal phenomenons are referred to as illusions by Professor E. Gadd and King Boo is referred to as the Master of Illusions much later in the game. It could be possible that the previous game's final boss fight was some sort of illusion Luigi was trapped in and had to fight his way through in order to save his brother. (Perhaps the same could be said for the titular fake mansion itself.)

Booette
Just like Bowsette, Booette is a fan-made form of King Boo (or regular Boos) which was created uploaded onto the internet. On September 13th, 2018 Nintendo created their new trailer for the video game New Super Mario Bros. U Deluxe. In the trailer, a new power is seen for Toadette named the Super Crown. When Toadette uses this power, she transforms into Princess Peach.

After the trailer, On September 19th, 2018, a Twitter user posted a comic, from which Bowsette and Booette originate. After Mario and Bowsette made Peach jealous, Luigi is seen thinking of doing the same thing to Princess Daisy. Which he did, he gave the crown to King Boo, making Booette a reality.

Trivia

 * King Boo's quote, "I don't plan to give up my favorite decoration. I like Mario where he is." is a quote derived from Star Wars VI: Return of the Jedi, when Jabba the Hutt said, "I don't plan to give up my favorite decoration. I like Captain Solo where he is."
 * Luigi is canonically the only Mario character to fight King Boo more than once, due to King Boo being his arch-enemy.
 * In the English version of Super Mario 64 DS, King Boo was mistranslated into Big Boo.
 * In the Mario Party 9 Sound Test, there are two voice sounds with the name "King Boo's Entrance"; one is King Boo and the other is actually Boo.
 * The Japanese, Dutch and Korean names for King Boo use the English word for king, instead of a word in their own dialects.
 * Although he commands a large band of Boos, not all Boos call King Boo their leader, with some Boos working directly for Bowser, and many others living peacefully with the other denizens of the Mushroom Kingdom, either independently or as part of a small band of Boos led by Lady Bow.
 * In the prerelease version of Luigi's Mansion, King Boo resembled Big Boo from Super Mario 64.
 * King Boo's Luigi's Mansion appearance also made an appearance in Mario Kart Tour.