King Boo

"Seriously, though, who would actually believe that mansions get given away in contests?! Talk about stupid! What do they feed you Mario brothers anyway... gullible soup?"

- King Boo

King Boo (Japanese: キングテレサ King Teresa) is the leader of the Boos and the main antagonist of the game Luigi's Mansion, where he first appears to be Luigi's nemesis. He is also an ally of Bowser, who has aided him in his various schemes. He is more than capable of devising and enacting villainous plans by himself, including his capture and imprisonment of Mario. Although not the biggest Boo in the Mushroom World, King Boo has abilities that far surpass that of the average ghost, and he wields a number of impressive magical abilities, including the ability to materialize objects. King Boo's magical power is directly proportional to the number of Boos in his vicinity.

Luigi's Mansion
Before the events in Luigi's Mansion, Professor E. Gadd, manages to capture Boolossus. This greatly angers the King Boo, and he plans to rescue Boolossus. Meanwhile, Professor E. Gadd brings Boolossus to his lab in Boo Woods. Using a device called a Ghost Portrificationizer, E. Gadd traps Boolossus in a portrait and hangs it in his Gallery.

Eventually, King Boo and his forces attack the laboratory. The Boos reverse the settings of the Portificationizer and release Boolossus. King Boo then orders that all the ghosts that E. Gadd has captured should be released. After releasing all the portrait ghosts and reversing years of E. Gadd's work, King Boo creates a huge mansion, and places it next to the professor's lab. King Boo, his Boo minions, and the portrait ghosts who are recently freed, decide to inhabit the mansion. With a new place to live in and an army of new ghosts created by the released portrait ghost Vincent Van Gore, King Boo decides to plan revenge against old rivals of the Boos to capture both Mario and Luigi.

Hoping to recapture Luigi, King Boo sends him a letter. The message states that Luigi has won a mansion in a contest and provides the location of the prize. Luigi is skeptical because he does not recall entering any contest; however, he is excited nonetheless. He asks his brother Mario to investigate the mansion and says that he will arrive shortly thereafter. As such, Mario, with Toad, enters the mansion. Then, Mario is instantly overwhelmed by King Boo's forces and captured. King Boo then imprisons him in a portrait, similar to how Boolossus was previously. Mario is placed in the Secret Altar in the basement of the mansion. However, King Boo wishes to add another painting to his collection, which is the portrait of Luigi.

While waiting for Luigi, King Boo and his Boo minions decide to wait behind a secret door in the floor of the Storage Room. When Luigi arrives in the room and reveals the secret door, the Boos spring out from the floor after being awakened from their slumber. However, the Boos (including King Boo) stop their surprise attack when they notice the Poltergust 3000 on Luigi's back. The ghost-capturing weapon was previously given to Luigi by Professor E. Gadd, who wants him to recapture the portrait ghosts. The Poltergust 3000 is one of the few things King Boo fears, and he and the other Boos scatter and hide in the mansion. King Boo travels to the Secret Altar in the mansion's basement. While in the room, King Boo amuses himself by watching Mario making his pleas for help.

Vincent Van Gore's special key locks the path to the Secret Altar. Vincent Van Gore has locked himself in the Artist's Studio on the third floor of the mansion. After capturing him and retrieving the key, Luigi discovers that he needs more than a key to access the Secret Altar. If Luigi attempts to enter the Secret Altar without catching a certain number of Boos, King Boo blows Luigi to the Foyer, the entrance of the mansion. However, since King Boo's power is related to the number of Boos in the mansion, Luigi can weaken him by capturing the Boos hidden in various rooms. After Luigi captures at least forty of the mansion's fifty Boos, King Boo loses his ability to blow Luigi from the Secret Altar. As such, with his Poltergust 3000 in hand, Luigi enters King Boo's Secret Altar.

Upon entering the altar, Luigi notices King Boo's staring at the Mario painting. However, King Boo turns to Luigi and states his desire to add a Luigi painting to the collection. After this, King Boo flies into the Mario painting hanging on the wall. The figure of Mario transforms into Bowser, and the new Bowser painting inhales Luigi into the canvas. After entering the painting, Luigi is transported into an arena that resembles the mansion's roof. Luigi then confronts Bowser. In reality, this is a mecha decoy of Bowser, but King Boo is piloting it inside.

King Boo uses this Bowser disguise to attack Luigi, shooting flames at him, and even attempting to inhale him into its mouth. The decoy also has the ability to create three large spiked bombs and toss the explosives at Luigi. Luigi can use his Poltergust 3000 take one of the spiked explosives and release it into the mecha Bowser's mouth. This attack blasts off the head of the mechanical Bowser decoy, making King Boo float outside. Exposed to the Poltergust 3000, Luigi begins to deplete the ghost's five hundred hit points. Meanwhile, the machine's head hovers around the arena, shooting icy blasts at Luigi. If frozen, Luigi can shake himself free while taking damage every second he is frozen. Eventually, King Boo flies back into the dormant Bowser body and the head reattachs itself, resuming the fight. Luigi repeats this process, slowly weakening King Boo, but after King Boo's life falls below two hundred HP, the head of the machine reattaches backwards whenever he returns to the Bowser body, causing the Bowser mecha to run around aimlessly. Eventually, the mecha puts its head on correctly and resumes the fight.

After this battle, Luigi manages to completely drain King Boo's HP and capture him inside the Poltergust 3000. King Boo, the Bowser mech collapses onto the ground with its head detached from its body.

After the battle, Luigi receives King Boo's crown, worth 5000G (the value of only one Gold Coin) and adds it to his treasure collection. Upon returning to the mansion, he also gets the Mario painting and quickly travels to Professor E. Gadd's lab. In the lab, Luigi connects the Poltergust to the professor's Portrificationizer, dumping its contents into the machine. Surprisingly, not only did the spirit of King Boo appear in the Portrificationizer, but also the Bowser mech. With King Boo captured, Professor E. Gadd hangs his new portrait in an empty room in his gallery. In the end, Mario is released from his portrait.

Luigi's Mansion 2
King Boo has been confirmed to appear in the 3DS game, Luigi's Mansion 2, possibly as the main antagonist. As seen in the official art, King Boo's design has reverted to the look he had in his debut in the first game, unlike more recent titles, where he appears simply as a large Boo with a crown, although he retains the full row of teeth added in later appearances. He is also much bigger than before.

Super Mario 64 DS
King Boo appears in the Super Mario 64 remake, Super Mario 64 DS. As the boss who locked Luigi away, he captures a part of Princess Peach's Castle. However, when the game is translated to English, King Boo is given the incorrect title, Big Boo. In Mario Kart DS, he returns with other Super Mario 64 DS bosses. He is given the proper name of King Boo, as he was in the Japanese version.

Regardless, King Boo aids Bowser in his conquest of Peach's Castle by capturing Luigi and imprisoning him in Big Boo's Haunt. Specifically, Luigi is imprisoned behind a painting of himself inside the haunted mansion. Mario eventually fights King Boo to free Luigi. To defeat King Boo, Mario has to follow King Boo's movements in the arena's mirror and to stomp him when he comes too close. Ultimately, Mario saves his brother from King Boo and together (with Yoshi and after Wario is saved) they defeat Bowser and save Princess Peach.

Super Mario Sunshine
A different "King Boo" is the leader of the Boos on Isle Delfino and appears as a boss in Sirena Beach, the sixth world of Super Mario Sunshine. He is apparently made from yellow goop, as can be seen during his defeat, meaning that Bowser Jr. might have drawn him. This game also notes that he dislikes spicy food, which serves as the key to defeat him.

He is named King Boo by the American localization team. However, the original Japanese version assigns a unique name to this character (ボステレサ, meaning Boss Boo), signifying that this King Boo is a separate character from the King Boo that appears in Luigi's Mansion.

Mario Kart: Double Dash!!
King Boo is an unlockable character in the racing game Mario Kart: Double Dash!!. This is his first appearance in a spin-off. This results in his frequent appearances in the Mario Kart series (he appears as a playable character in every Mario Kart following this game except for the DS version, where he appeared as a boss in a mission, and Mario Kart 7, where he does not appear at all). Despite being a ghost, King Boo is classified as a heavyweight driver due to his large size. His partner is Petey Piranha, and both have the ability to use any other character's special item (if they are going to get a special item, it is randomly chosen, based on their race position). This means that they possess no unique special item of their own.

King Boo's personal kart is the Boo Pipes, which is a gray version of Petey's Piranha Pipes kart, but with an image of a Boo instead of a Piranha Plant where the item-using partner stands. However, the more important difference between the two is that, while the Piranha Pipes has high speed and low acceleration, the Boo Pipes has it the other way (it has low speed and high acceleration), which is quite odd for a heavy kart.

Oddly, when partnered with Petey Piranha, King Boo appears smaller than Petey. This is most noticeable before the race starts if he is not the driver. Yet, if partnered with another character, he appears much larger than the other character. He also appears to slightly shrink when he becomes the driver. On the second "Thanks for Playing!" screen (after beating the Special Cup with a Gold Trophy while all other cups already have a Gold Trophy), King Boo appears chasing Wario and Waluigi.

Mario Kart DS
In the game Mario Kart DS, King Boo battles against Princess Peach in Mission mode. Peach attempts to collect fifty coins on the Lava Arena but after a few seconds King Boo then surrounds and attacks her, stealing ten of her coins and making all the other, uncollected coins disappear. To take them back, Peach has to drive and hit King Boo, making him transparent. Then, she can drive through him again, retrieving her coins and making the other coins reappear. However, King Boo soon reappears a few moments later to get the coins again. After collecting all fifty coins, Peach finally defeats King Boo.

Mario Kart Wii
King Boo returns in Mario Kart Wii as a large-sized driver, and is unlocked by completing the Star Cup in 50cc. He features a good handling bonus and a small off-road bonus, which comes in handy for vehicles like the Offroader, Wario Bike, and Phantom. He is used as the Staff Ghost on the SNES Ghost Valley 2 course. In the credits, he appears driving the Aero Glider on the SNES Ghost Valley 2 course.

King Boo is one of very few characters to have his standing animation (on the Character Select screen) altered from Mario Kart: Double Dash!! In this case, his tongue is not sticking out of his mouth the whole time like before; now, before selecting him, his tongue would be in his mouth. Other characters whose sprites were altered include Birdo (whose bow was made larger), Wario (who now has short sleeves), and Waluigi (what he does when being selected in Mario Kart Wii seems much different from Mario Kart: Double Dash!!).

Mario Superstar Baseball
King Boo is a playable character in Mario Superstar Baseball and a member of Wario's baseball team. He does not need to be unlocked. He is a power hitter; he can use his white, Boo-like baseball bat (topped with a crown) to hit long outfield drives and even homeruns. King Boo has chemistry with Boo and Petey Piranha, and he has bad chemistry with Luigi. However, like Boo, his hits are usually very curved and cause them to be fouls most of the time.

Mario Super Sluggers
King Boo reappears in Mario Super Sluggers and is once again a member of Wario's baseball team. In Challenge Mode, he appears immediately after the player defeats Bowser Jr. at the Wario City stadium. However, he is uninterested in joining the player's team unless the team has some Boos with them. This is accomplished by finding both Boo and the Mini Boos (an item). In this game, King Boo has chemistry with Petey Piranha, Boo, King K. Rool, and Wiggler, but he has bad chemistry with Mario, Luigi, Baby Mario, and Baby Luigi.

An interesting thing to note is that his baseball bat does not have a physical crown on it anymore. In this game, it is represented as a crown picture above the "Boo mouth" picture.

Super Princess Peach
King Boo aids Bowser in Super Princess Peach. In this game, Bowser's forces capture both Mario and Luigi with some Toads. Although King Boo does not directly watch over Mario or Luigi, he is given a captured Toad to guard (Mario is Bowser's prisoner, while Luigi is Kamek's prisoner.)

After adventuring through Vibe Island, Peach discovers where King Boo is and engages him in combat. During the battle, King Boo fires blue homing fireballs at Peach. Peach can damage King Boo with direct light, which is made by having his own flames light candles. After a few attacks, King Boo uses his Gloom vibe. He cries, which extinguishes the candle flames. After enough attacks, King Boo is eventually defeated. With King Boo eliminated, Peach rescues the Toad and continues against Bowser's forces. Ultimately, Peach defeats both Kamek and Bowser and rescues Mario and Luigi.

In this game, King Boo is described (and appears) as a huge Boo, suggesting that he may not be the same as the original King Boo from Luigi's Mansion.

Mario Party 8
King Boo makes his first appearance in a Mario Party game in Mario Party 8. He is the star-giver of his own course King Boo's Haunted Hideaway. He hides in one out of three altars and he gives the player a Star for ten coins if he or she can find him where he is hiding. Afterwards, he may "summon the bizarre" and disappear, causing the player to jump into a Warp Pipe to the starting point. This "makeover mojo" causes the whole layout of the course to change. Additionally, when the players loses the mini-game Pickpocket Pinball, the mouse sounds like King Boo. The player can purchase King Boo sounds from the Fun Bazaar with a figurine titled "King Boo's Revenge".

Mario Party 9
King Boo appears as the boss of the board Boo's Horror Castle in Mario Party 9. He is fought in the minigame King Boo's Puzzle Attack, where the competitors line up power-ups in lines of 3 or more to deal damage to him.

Mario & Sonic at the Olympic Winter Games
King Boo appears as the first and sixth (in Individual Festival mode) rival in Mario & Sonic at the Olympic Winter Games. King Boo races the player in Alpine Skiing Downhill in both Individual and Group Festival modes but he only races the player in Giant Slalom in the Individual Festival mode. King Boo has no skis so he goes down the hill smoothly. If the player loses to him, the guide (either Cream or Toad) says that it is unfair because King Boo has no skis.

In Adventure Tours in the DS version, King Boo is the boss of Polastraits. When the challenger approaches him, King Boo challenges Luigi to an Alpine Skiing Downhill race because Luigi attacked his minions earlier. In this version, King Boo is transparent and the player can ski through him. He also appears slightly larger than in his other appearances.

''Mario & Sonic at the London 2012 Olympic Games
King Boo once again, appears in Mario and Sonic at the London 2012 Olympic Games. He is one of the characters that can be found in the London Party mode and a rival of the Dream Sprint event. If the player reaches the goal line before him, he or she will get a sticker as award. In the 3DS version, King Boo teams up with a Boo to face Sonic and Tails in the event Badminton (Doubles). After winning, the player finally completes Sonic's second episode.

Physical Appearance
King Boo's appearance has changed throughout his video game history. In his debut in Luigi's Mansion, King Boo has dark, red eyes, a blue tongue, two vampire-like fangs, a purplish complexion, and a ruby crown. In recent appearances, he resembles a white Big Boo with a golden crown (though much larger), as he did in the "Big Boo Battle" in Super Mario 64 DS, which remains as his current appearance to this day (though artwork for Luigi's Mansion 2 shows him with his Ruby Crown).

Personality
King Boo is shown to not hold a grudge, even when Luigi defeats him in Luigi's Mansion. He is one of Bowser's most trusted minions because of his intelligence and power. He also says that he fears nothing except the Poltergust 3000, although in Super Mario 64 DS he admits that Wario scares him, rendering the previous statement a generalization. Also, in Mario Super Sluggers, King Boo says that he finds little Boos cute. In Mario & Sonic at the Olympic Winter Games, he says that he is unbeatable at the Alpine Skiing events, though this is proven false when the player beats him.

Traits and Abilities
Besides possessing the abilities of other Boos, including the ability to teleport, King Boo has a number of other powers. Notably, King Boo's power increases when he is in the presence of other Boos. For example, King Boo has the power to blow Luigi to the Foyer when enough Boos are in the mansion. King Boo also has the power to materialize things, including mansions and lifelike robotic replicas of some of Mario's enemies. He has also shown the ability to create Boos, bubbles, and blue fire, which he spits out of his mouth. King Boo also appears to be a good Alpine Skier, as he states that he is exceptional at that event, though this remains questionable due to his lack of skis.

Although King Boo is much 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. King Boo may have a passion for gambling, as the entrance to each wing in Luigi's Mansion is modeled after a playing card suit (spade, club, heart, and diamond). King Boo appears with a rather high power stat in many of his spin-off appearances. This is most noticeable in the Mario Baseball series, where he is able to hit home runs with relative ease.

King Boo has an extreme dislike for the Mario Bros., due to their constant intervention in his plans and others of his kind. Lastly, King Boo has a distinct cackle, which is significantly lower in pitch than other Boos.

King Boo is also shown to be able to regenerate from his crown in Super Princess Peach.

Boo Leadership
Although he commands a large band of Boos, not all Boos call King Boo their leader. Some Boos work directly for Bowser. These Boos are most likely the Boo enemies that have appeared in earlier games before King Boo's debut. A small band of Boos are allied with Lady Bow; these ghosts live peacefully with the other denizens of the Mushroom Kingdom (although they still like to scare other species, especially Toads, from time to time).

Mario
King Boo and Mario have known each other for a long time. Also, King Boo imprisons Mario in a painting as a consequence for foiling his plans in the past.

Luigi
When Mario goes to Luigi's new mansion to investigate, he is captured by King Boo. Therefore, Luigi has to go rescue Mario by defeating the Boo leader. King Boo longs for Luigi in the painting too, for Luigi also has past dealings with King Boo. Ever since Luigi's Mansion, the two have shared bad chemistry.

Petey Piranha
Petey Piranha and King Boo have shared chemistry in many spin-off games; the two are default partners in Mario Kart: Double Dash!! and they share chemistry in both Mario Superstar Baseball and Mario Super Sluggers. Though the two appear to be friends, their relationship with each other still remains quite a mystery.

Bowser
King Boo is known to be one of Bowser's right-hand men due to his intelligence and power over Boos. This was shown in Super Mario 64 DS where he was guarding Luigi's key. Also, King Boo was one of the bosses in Super Princess Peach, a game where Bowser had kidnapped the Mario Bros., so he must've called upon King Boo to hinder Peach's quest. Also, in Luigi's Mansion, King Boo participates in the final battle in a Bowser decoy (most likely a False Bowser), which he controls. It breathes fire and spits out large mines. Since King Boo was allowed to use a giant mecha that merely looks like Bowser, he might have given the Boo his permission to use it; on the contrary, King Boo might have constructed it without Bowser's knowledge.

Wario
Though no direct interactions have been shown, King Boo and Wario seem to have something to do with each other. In the ending picture to Mario Kart: Double Dash!!, King Boo is shown chasing Wario and Waluigi, scaring the two. Also, in both Mario Baseball installments, King Boo is on Wario's team, though this may not be very reliable since Wario's team may be considered the "misfit team"; there is no noticeable theme through his team (Mario's is Delfino-based, Peach's is Toad-based, DK has characters from the DK Series, and Bowser has his minions).

Professor E. Gadd
King Boo originally stated that the only thing that scared him was the Poltergust 3000, which Prof. E. Gadd has invented. Also, before the events of Luigi's Mansion, Prof. E. Gadd has captured one of King Boo's greatest minions, Boolossus. Therefore, King Boo plots an attack on Prof. E. Gadd's laboratory and sets free all of Gadd's years of ghost-capturing work. This shows that King Boo and Prof. E. Gadd are not on good terms with each other.

Quotes

 * "White gloves! A cute little moustache! Soft shoes! How did you get out of my...? ... Huh? Wait just a second... Your clothes are... green... Hey, you must be Luigi! Whoa, you had me a bit confused for a moment there!" - Luigi's Mansion
 * "What? You want me to release Mario? Riiiiight." - Luigi's Mansion
 * "It's true what they say about fine art... it takes utterly refined sensibilities to truly appreciate it!" - Luigi's Mansion
 * "The way you plead for help, Mario... I find it so... satisfying." - Luigi's Mansion
 * "...Seriously, though, who would actually believe that mansions get given away in contests?! Talk about stupid! What do they feed you Mario brothers anyway... gullible soup?" - Luigi's Mansion
 * "I swear it... I shall fear no mere house-cleaning device!!" - Luigi's Mansion
 * "There are no exits. You may as well wander in here forever..." - Super Mario 64 DS
 * "I love scaring wimpy humans." - Super Mario 64 DS
 * "Eek! What's this!? Your face... It would even scare a ghost. How horrible! You've got it backwards... I do the scaring around here!" - Super Mario 64 DS
 * "Aw... Little Boos are so cute!" - Mario Super Sluggers
 * "Bring me my 10 coins fools!" - Mario Party 8
 * "If you hear me laughing, that means you're doomed!" - Super Mario 64 DS

Mario Kart: Double Dash!!
Website Bio: ''If you're not afraid of ghosts, you will be once King Boo is through with you. To unlock him, finish the Mirror Mode Star Cup with a 1st place win.''

Mario Kart Wii

 * Size: Large
 * Actual Bonuses
 * Handling: +5
 * Off-road: +3

Mario Super Sluggers

 * Team Captain: No
 * Player Type: Power
 *  Special Skill: Teleport
 * Good Chemistry: Boo, King K. Rool, Petey Piranha, White Mii, Wiggler
 * Bad Chemistry: Baby Luigi, Baby Mario, Luigi
 * Stats
 * Batting: 7/10
 * Pitching: 7/10
 * Fielding: 3/10
 * Running: 4/10
 * Default Bat: Right
 * Default Glove: Left
 * In-Game Bio: A decent player with poor defense.
 * Collectible Card Info: Haunting Luigi since he first set foot in the mansion, King Boo doesn't have the stamina for late innings, but he's a talented player nonetheless. As it is with many ghosts, he is not well-liked by other players.

Trivia

 * When King Boo says, "I don't plan to give up my favorite decoration. I like Mario where he is.", it is a quote derived from Star Wars VI Return of the Jedi, when Jabba said, "I don't plan to give up my favorite decoration. I like Captain Solo where he is."
 * For some reason, King Boo's voice is sometimes sped up in games like Mario Kart: Double Dash!!, Mario Kart Wii, and Mario Super Sluggers, while in such games like Super Mario 64 DS, and Mario Kart DS, it is unaltered. This is quite similar to Bowser's voice being slowed down in some games, while in others it is not.
 * If King Boo is captured in a Silver or Bronze Frame, the portrait shows him wearing his crown, even though Luigi has taken it when he traps King Boo in the Poltergust 3000.
 * The mechanical Bowser decoy that King Boo utilizes against Luigi may be loosely based on the False Bowsers from Super Mario Bros..