King Boo is the king of all Boos, and although he is not the biggest Boo, he is the most powerful of his kind. The only staff time trials course dedicated to him is SNES Ghost Valley 2 (Mario Kart Wii). He is very sneaky and can summon anyone's special item in Mario Kart: Double Dash!!. He is an unlockable character in Mario Kart: Double Dash!! and Mario Kart Wii. In Mario Kart DS, he is a boss in Mission Mode, and like all bosses he came from Super Mario 64 DS, but was mistakenly called Big Boo in Super Mario 64 DS.
Despite being an excellent handler, King Boo is a mid-tier character for his poor raising stats. King Boo is often used for courses with tight turns, such as Rainbow Road. Although in the mid-tier placing, King Boo has excellent rivalries with other characters and has excellent racing skills, making him a character with high-tier or highly possible, top-tier character categories since his handling stat raises any kart or bike, including the Spear. He was never a default playable character until Mario Kart 8 Deluxe.
- Mario Kart: Double Dash!!: Finish the Star Cup in Mirror Mode.
- Mario Kart Wii: Finish the Star Cup on 50cc, or play 750 races.
King Boo is the king of all the Boos. His body is a ghostly white color. Most likely because he is a ghost. He has a round shape with two arms on either side of his body (or face, it's tough to tell), and he has a tail. He always has his mouth open in a haunting manner, so his tongue and sharp teeth can be seen quite clearly. He has black eyes. So, with that being said, what makes him different from a regular Boo? He is noticeably bigger, and he has a royal golden crown with red and blue jewels encrusted in it. Try to take away his crown, and he will haunt you for the rest of your life!
- Boo Pipes
- Standard Kart L
- Flame Flyer
- Piranha Prowler
- Wario Bike
- Standard Bike L
- Flame Runner
- Shooting Star
Staff Ghost Tracks
* - Retro track
- Interestingly, King Boo is one of the heavyweight characters, despite being a floating, weightless ghost. This may mean that his crown weighs a lot or because of his large size.
- Despite being a "weightless" heavyweight, King Boo is heavier than Wario and Waluigi, the same weight as Rosalina and slightly heavier than Dry Bowser.
- King Boo is the only character in Mario Kart: Double Dash!! to not yell when being shot from the cannon in DK Mountain (though in Mario Kart Wii, he does).
- It is unclear why Nintendo put King Boo in Mario Kart Wii since he's unable to drive any karts in the game due to having no legs.
- King Boo was confirmed as a returning character in Mario Kart 8 Deluxe, along with Bowser Jr. and Dry Bones.
- He, along with Petey Piranha, can use every racer's special item in Mario Kart: Double Dash!!
|Light||Baby Mario • Baby Luigi • Toad • Toadette • Koopa Troopa • Koopa Paratroopa • Diddy Kong • Bowser Jr.|
|Medium||Mario • Luigi • Peach • Daisy • Yoshi • Birdo • Waluigi|
|Heavy||Wario • Donkey Kong • Bowser • King Boo • Petey Piranha|
|Mario Kart Wii characters|
|Small||Baby Mario • Baby Luigi • Baby Peach • Baby Daisy • Toad • Toadette • Koopa Troopa • Dry Bones|
|Medium||Mario • Luigi • Peach • Daisy • Yoshi • Birdo • Diddy Kong • Bowser Jr.|
|Large||Wario • Waluigi • Donkey Kong • Bowser • King Boo • Rosalina • Funky Kong • Dry Bowser|
|Mario Kart 8 / Deluxe racers|
|Light||Baby Mario • Baby Luigi • Baby Peach • Baby Daisy • Baby Rosalina • Toad • Toadette • Koopa Troopa • Shy Guy • Lakitu • Larry Koopa • Wendy O. Koopa • Lemmy Koopa • Isabelle+ • Villager+ • Dry Bones* • Bowser Jr.*|
|Medium||Mario • Luigi • Peach • Daisy • Yoshi • Ludwig von Koopa • Iggy Koopa • Tanooki Mario+ • Cat Peach+ • Inklings*|
|Heavy||Wario • Waluigi • Donkey Kong • Rosalina • Bowser • Roy Koopa • Morton Koopa Jr. • Metal Mario • Pink Gold Peach • Link+ • Dry Bowser+ • King Boo* • Gold Mario*|
|+ - denotes DLC. • * - denotes exclusivity to Mario Kart 8 Deluxe.|