King Boo

King Boo is a character from the Mario franchise. He is a large, round ghost who serves as the leader of the Boos. King Boo makes his debut appearance in Luigi's Mansion as the main antagonist, and he serves as Luigi's arch-nemesis throughout the Luigi's Mansion series. King Boo's recurring design was introduced in Mario Kart: Double Dash!!, and is sometimes considered to be separate from the King Boo in the Luigi's Mansion series.

Like a majority of Mario characters, King Boo's only Sega-related appearances are in the Mario & Sonic series, in which he debuted in both the Wii and Nintendo DS versions of Mario & Sonic at the Olympic Winter Games. In the Mario & Sonic series, like most other Mario titles, King Boo uses his design introduced in Mario Kart: Double Dash!!, and his artwork from Mario Super Sluggers is reused for the Mario & Sonic series.

Mario & Sonic at the Olympic Winter Games (Wii)
In the Wii version of Mario & Sonic at the Olympic Winter Games, King Boo appears as the first and sixth (in Individual Festival mode only) rival. King Boo races the player in the Alpine Skiing Downhill event 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.

Mario & Sonic at the Olympic Winter Games (Nintendo DS)
In the Nintendo DS version of Mario & Sonic at the Olympic Winter Games, King Boo is the mid-boss of Polastraits in Adventure Tours mode. When the character in play (Mario or Sonic) approaches King Boo, he tells them that he must race someone afraid of him. King Boo notices that Luigi is scared of him, and decides for Luigi to compete against him in Alpine Skiing GS. In this version, King Boo is transparent, allowing for Luigi to ski through him. King Boo is also slightly larger than in his other appearances.

Mario & Sonic at the London 2012 Olympic Games (Wii)
In the Wii version of Mario & Sonic at the London 2012 Olympic Games, King Boo is one of the rival characters that can be found in the London Party mode, and when he is encountered, he challenges the player to the Dream Sprint event, with stickers being offered as a reward for beating him.

King Boo, along with Boo and Magikoopa, are the only three characters who appear as rivals in Mario & Sonic at the London 2012 Olympic Games to not appear as playable characters in any version of Mario & Sonic at the Rio 2016 Olympic Games.

Mario & Sonic at the London 2012 Olympic Games (Nintendo 3DS)
In the Nintendo 3DS version of Mario & Sonic at the London 2012 Olympic Games, King Boo appears in the Story Mode, where he helps guard the Phantasmal Fog at the Tower of London, and teams up with a Boo to challenge Sonic and Tails in Badminton (Doubles). When defeated, he and the Boo flee, and King Boo later appears at the opening ceremony for the games. A badge of King Boo can also be obtained from the badge machine.

Mario & Sonic at the Sochi 2014 Olympic Winter Games
King Boo appears in Mario & Sonic at the Sochi 2014 Olympic Winter Games as a rival in the Legends Showdown mode. He is found in Area 4, and is raced against in Short Track Speed Skating 1000m.

Physical appearance and traits
Since his debut in Mario Kart: Double Dash!!, King Boo resembles a normal white Boo with a golden, five-pointed crown, though he is noticeably larger, sometimes at or exceeding the size of a Big Boo. With this design, the crown has a blue jewel on the front and four red jewels around the sides. Like other Boos, King Boo is generally shown with an open, wide grin, Generally, while being looked at, King Boo closes his mouth and bashfully covers his face with his hands. King Boo has a distinct cackle, which is significantly lower in pitch than other Boos. He also has an echo in his roar.

Personality
The Mario & Sonic series shows more of King Boo's personality than in most Mario titles, save for the Luigi's Mansion series. In the Nintendo DS version of Mario & Sonic at the Olympic Winter Games, King Boo specifically chooses Luigi to race against in an Alpine Skiing GS event because Luigi is afraid of ghosts. This is one of the only instances where King Boo's rivalry with Luigi is shown.

In the Mario & Sonic series, King Boo has a superiority complex and is quite prideful. In the Wii version of Mario & Sonic at the Olympic Winter Games, King Boo claims that he is unbeatable at the Alpine Skiing event. In the Nintendo 3DS version of Mario & Sonic at the London 2012 Olympic Games, King Boo claims to have beaten Mario before.

Mario & Sonic at the Olympic Winter Games

 * "You?! I might have known. Just what I need, some fool who ain't afraid of a ghost! My little Boos came crying to me about you... Outrageous!" - Mario & Sonic at the Olympic Winter Games (Nintendo DS)
 * "I'd rather go up against someone who's scared of ghosts though! Hee hee hee!"
 * "I don't believe it! You won! I've finally met my match!"
 * "Heh heh heh! I saw that Alpine Downhill event of yours yesterday! Looks like you need to take a lesson in speed from ME! And that lesson starts today! I challenge you to an Alpine Downhill match! Hee hee hee!" - Mario & Sonic at the Olympic Winter Games (Wii)
 * "I felt sorry for you and let you win the Alpine Downhill event, but it's not going to happen this time! When it comes to the Alpine Giant Slalom, I’m number one! Heh heh heh!"