Boo

A Boo is a type of ghost in the Mario series. They first appeared in Super Mario Bros. 3, but in Super Mario World, there were Ghost Houses, which contained many Boos.

The Boo's Mansion in Paper Mario was a bigger version of the Ghost Houses, which had many puzzles involving Boos in it. After solving these puzzles, Bow, the princess of the Boos, joins Mario's team. In Paper Mario: The Thousand Year Door, she and Bootler are on vacation in Poshley Heights after Mario and his teammates defeat the Shadow Queen.

In Luigi's Mansion, there are 51 Boos which Luigi must suck up in his Poltergust 3000. There are 50 regular Boos, 15 of them making up Boolossus, and there is also King Boo.

In the Mario Kart series, the Boo is used as an offensive and defensive item. When activated, the Boo selects a random target, steals his item and gives it to you, and then makes you invisible and invulnerable for a short period of time.

In Paper Mario: The Thousand Year Door, the Boos live in a tower called Creepy Steeple. When Mario Spin Attacks them, they merge into the Atomic Boo.

Boo appears as a playable character in Mario Party 5, Mario Party 6, Mario Party 7, Mario Golf: Toadstool Tour, Mario Superstar Baseball, and Mario Power Tennis.

It is unknown if Boos are the ghosts of formerly living beings or if they are an actual species.

Sub-Species

 * Balloon Boo: A balloon-like Boo, which inflates when looked at and deflates when looked away from. Seen in New Super Mario Bros. in level 4-Ghost House.


 * Dark Boo: A purple stronger Boo that's found in Poshley Sanctum.


 * Stretch: A platform made of ghosts.


 * Boo Guy: The ghost version of a Shy Guy.


 * Boo Man Bluff: A blindfolded Boo that moves toward your noises.


 * Boo Balloon: Hit it three times with eggs to defeat it in Yoshi's Island.


 * Boo Blah: A ghost that moves on floors and ceilings, then pops up.


 * Boo Block: A Boo that turns into a block if you look at it.


 * Boo Buddy Snake: A chain of Boo's that bounce off surfaces endlessly.


 * Big Blue Boo: Boss of Donut Plains Secret Ghost House.


 * Big Boo: A huge Boo that acts the same as regular Boo's.


 * Circling Boo Buddies: A circle of Boo's with a small gap to let you pass through.


 * Disappearing Boo Buddies: A large group of vannishing Boo's


 * Fishin' Boo: A boo that holds a fishing rod with an item, or flames, attached to the end, much like the fishin' Lakitu

Notable Boos

 * Bow - Paper Mario
 * Bootler - Paper Mario
 * Big Boo - Super Mario World
 * Bigger Boo - Yoshi's Island
 * King Boo - Luigi's Mansion
 * Lahla - Paper Mario: The Thousand-Year Door
 * Peeka - Paper Mario: The Thousand-Year Door
 * Stanley - Paper Mario

Tools

 * Boo's Sheet - Paper Mario: The Thousand-Year Door
 * Fright Bomb - Super Mario RPG: Legend of the Seven Stars

Mario Superstar Baseball Bio
"Bowser's underling ghost. Behind the scary face lies a shy soul. Look most Boos in the eyes and they'll cover their faces... but turn around and they'll attack you! Boos confuse their enemies by flickering in and out of the visible realm, appearing at inconvinient times."

Boo's Stats and Tattle Information, Paper Mario: The Thousand Year Door

 * Stats: HP 7, Attack 3, Defense 0
 * Tattle: That's a Boo. It's everyone's favorite ghost. ...Well, most everyone... It's nothing to write home about on the Attack side, but it can turn invisible. If it turns invisible, we won't be able to hit it, so beat it while you can see it. Boos are kinda cute, but I sure wouldn't want to meet one in a dark alley. If I ran into one in the bathroom in the middle of the night, I'd... Well, never you mind what I'd do.
 * Tattle Number: 71
 * Tattle Log: A somewhat shy ghost that can make itself and its allies invisible. It may be a ghost, but it's pretty cute.

Atomic Boo's Stats and Tattle Information, Paper Mario: The Thousand Year Door

 * Stats: HP 40, Attack 4, Defense 0
 * Tattle: That's an Atomic Boo. It's a giant Boo made up of a ton of smaller Boos. This thing will try to smoosh us. It can also split up and send hundreds of Boos at us. And, when we attack, we might get so scared that we get confused or can't move. I sure wouldn't want to see this thing standing behind me in the middle of the night... Creeeeeepy...
 * Tattle Number: 72
 * Tattle Log: A massive creature made up of countless Boos. It attacks by breaking apart and sending out hundreds of Boos.

Dark Boo's Stats and Tattle Information, Paper Mario: The Thousand Year Door

 * Stats: HP 8, Attack 5, Defense 0
 * Tattle: That's a Dark Boo. Purple just looks... so wrong. These Boos are SO creepy. Its HP and Attack are high, but they're just like ordinary Boos otherwise. So, just attack it like a normal Boo. Get it before it turns invisible!
 * Tattle Number: 73
 * Tattle Log: A creepy-looking Boo with high HP and Attack. Get it before it turns invisible!

Lil' Boo's Stats, Super Mario RPG

 * HP 66
 * Attack 120
 * Defense 20
 * Magic Attack 74
 * Magic Defense 120

The Big Boo's Stats, Super Mario RPG

 * HP 43
 * Attack 18
 * Defense 0
 * Magic Attack 18
 * Magic Defense 24

Quotes

 * Wanna play GameBoo Advance? - Luigi's Mansion
 * Check those bubbles coming out of his nose! - SMRPG 
 * Hi, I'm Luigi! I mean, Booigi! - Luigi's Mansion
 * Time for the six o' clock Boos! - Luigi's Mansion