Boo

This article is not to be confused with the replays of previous Time Trial attempts known as, Ghosts.

This article is not to be confused with the character, King Boo.

Boo
Information
Description	An Item that can steal another racer's Item and make the user invisible.
First Appearance	Super Mario Kart (1992)
Most Recent Appearance	Mario Kart 8 Deluxe (2017)

A Boo is a haunting enemy in the Mario series. It makes its appearance in the Mario Kart series as an item, first in Super Mario Kart, and then in Mario Kart 64, Mario Kart: Super Circuit, Mario Kart DS, and Mario Kart 8 Deluxe. The item is also in the arcade games Mario Kart Arcade GP and Mario Kart Arcade GP 2.

Boos are also harmless (but still scary) characters that fly around in courses such as Ghost Valley 1, Ghost Valley 2, Ghost Valley 3, and Banshee Boardwalk. However, they are dangerous on Broken Pier in Mario Kart: Super Circuit, because encroaching on their territory will cause one to grab onto you and make you lose speed and Coins.

The Boo item temporarily left the Mario Kart series for 12 years, and then came back to Mario Kart 8 Deluxe. Boo will Steal your Items instead

Mario in posession of a Boo item.

Uses

A Boo, probably the sneakiest Item in Mario Kart, temporarily turns the racer who is using it completely invisible to all other opponents. The player themselves sees their kart turn into a ghost, similar to the ones in Time Trials. While invisible, the racer cannot be hit by any Items whatsoever, and they are also not hindered by driving off-road. However, they still bump into walls likely to prevent cheating and can drive off the track, but it is still extremely convenient for cutting corners and avoiding incoming Items, making a Boo a great recovery and defensive Item.

In addition to invisibility, a Boo will go and fly off to another racer who has an Item. They will steal it, and then fly back to bring it to you (which is perfectly legal). It could be anything such as a Starman or a Green Shell, depending on whatever the other opponents have. In all games except for Mario Kart 8 Deluxe, it will steal the strongest item in play, and in Super Mario Kart, the steal will work even if the opponent's Item Roulette has not yet stopped. If no one has anything, the player does not get any items. But the Boo will still come back to say goodbye. It just will not deposit anything in your Item inventory.

In Mario Kart 8 Deluxe, Boo will steal from the main item slot of a random racer who is ahead of the user, and place it in the user's reserve slot. Fire Flowers, Boomerang Flowers, Golden Dash Mushrooms and Triple items will be fully restored as if the player had just gotten them from the Item Box. It will not steal Piranha Plants or Bullet Bills that are currently in use, nor will it steal Crazy 8s or other Boos as it is impossible to have more than one in play at a time. If there is nothing to steal, the Boo will give its user a free Mushroom. The invisibility no longer prevents slowdown from driving off-road.

Super Mario Kart

The Boo, originally known as Ghost, makes its first appearance in Super Mario Kart as both an item and a background element in the Ghost Valley courses. As an item, the Ghosts only appear in 2-Player races where they, upon use, pilfer an item from an opponent and make the user invisible. If there aren't any items to steal, the Ghost will stick its tongue out at the player and vanish from the Item Box.

In the Ghost Valley courses, the Ghosts float in the background laughing at the player as they race.

Mario Kart 64

The Boo returns as an item and a background element in Mario Kart 64. As an item, the Boo turns the user invisible and makes them invulnerable to all damage. They select an opponent to steal items from, but if there aren't any, the user will still get turned invisible, but they will not receive anything in return.

Computer-controlled drivers can also use the Boo, but they cannot steal items.

As a course element, several Boos float around portions of the track Banshee Boardwalk, in which they fade into view and float around the player while laughing. On Rainbow Road, a neon-light Boo appears as a background element, appearing into view, flashing twice, then turns off.

Mario Kart: Super Circuit

Boos once again appear as items and background elements in Mario Kart: Super Circuit. As an item, it makes the user invisible for five seconds and slows down the leader of the race, making them drop their Coins. Unlike Mario Kart 64, computer-controlled racers can now steal items from their opponents.

As a course element, several Boos appear in Boo Lake, holding candles to guide the players through the course and laughing if a player passes under them. In Broken Pier, the Boos instead float in place and slow down the racer who collides with them.

Trivia!

• In the Super Mario Kart instruction booklet, Boo was simply called a Ghost.
• Players can actually race as a Boo, specifically the regal King Boo, in Mario Kart: Double Dash!!, Mario Kart Wii, and Mario Kart 8 Deluxe.
• Nintendo removed the Boo from Mario Kart Wii and so forth. It had a long absence of 3 games, but it has returned in Mario Kart 8 Deluxe and has the same purpose stealing items and bringing them back to the user while making them invisible but this time, Boos are much more common with sometimes up to six appearances in one race. It's also notable that King Boo has been a returning racer.
• In the Mario Kart DS kiosk demo, the item texture used the Mario Kart 64 Boo sprite.

Gallery

A Mario Kart 64 Mario action figure with a Boo.

A Boo being helpful and lighting the way for Mario in Boo Lake.

Toad cowering in fear from Boos in the Broken Pier track.