Big Boos are a sub-species of Boo. Usually they resemble and behave similar to normal Boos, except that they are larger.
Super Mario WorldEdit
Big Boos first appeared in Super Mario World. In the game, Big Boos inhabited the various Ghost Houses located around Dinosaur Land. Curiously, although they are over ten times bigger than a normal Boo, Big Boos still have the same mannerisms of their smaller counterparts. Of course, this means that when looked at, a Big Boo will fade and hide behind its arms. However, if someone's back is turned, a Big Boo will attack him or her from behind.
In the game, Big Boos are much more difficult to pass than their smaller brethren. As such, Mario or Luigi usually have to use a trampoline to jump over these massive ghosts. However, if Mario or Luigi can get a running start, they can usually Spin Jump over a Big Boo. Additionally, if there is room, the brothers can use a cape to fly over a Big Boo or perform a sliding Cape Attack during descent to actually destroy the Big Boo. In the game, the ghost's proper name is "The Big Boo". additionally, one blue Big Boo, is a hidden boss of the secret Donut Plains Ghost House. He could be defeated by throwing Grab Blocks at his face. He had two normal Boos accompany him in battle.
In Hotel Mario, Big Boos, first appearing in Ludwig's Thump Castle Hotel, are powerful enemies, being about one-sixth the size of a hotel floor; Big Boos in this game attacked in a manner similar to the ones of Super Mario World, slowly floating towards Mario or Luigi when they look away, turning transparent when directly looked at
The big boo appears as the boss of the level Ghost mansion in Yoshi's Safari, Mario must shoot it with the Super Scope as he makes parts of the wall fall down on him. Later the boo will separate into 3 smaller Boos. Mario must shoot the one with his tongue out to win.
Super Mario RPG: Legend of the Seven StarsEdit
One Big Boo has a cameo appearance in this game - it is used in Bowser's Terrorize attack. The enemy, The Big Boo, is just a misnamed regular Boo.
Super Mario 64Edit
Big Boos return in the game Super Mario 64. Again, a Big Boo would disappear when looked at, and become visible again when Mario turns away. Big Boos can only be attacked when visible, so Mario had to attack these massive ghosts by either Ground Pounding them from above or punching them from the side. Regular Boos first appear in the courtyard of Princess Peach's Castle, and act the same way except less aggressive and requiring only one hit. One Boo is the keeper of Big Boo's Haunt, a miniature ghost house that shrinks the one who enters. Inside the ghost house, Mario can fight three more Big Boos. These Big Boos take three hits to defeat, becoming smaller after each hit. After destroying a Big Boo, Mario will receive a Power Star. In the Japanese version, the giant Boos are known as "Boss Teresa" rather than "Atomic Boo" (Big Boo's Japanese name). The giant Boo that appears when all the ghost house Boos are defeated is referred to is also known as "Master Teresa."
In the DS remake, Super Mario 64 DS, the leader of the Boos himself makes an appearance. In this game, King Boo has his trademark crown from later appearances and characteristic cackle. However, in game, he is erroneously referred to as Big Boo in English versions.
Mario party gamesEdit
In the Mario Party series, Big Boo makes a few appearances. In Mario Party 2 a Big Boo appears in the Horror Land stage. As a typical Boo, it is able to steal objects from player's rivals, being coins or stars. However, Big Boo will deal for stealing the coins or the stars from all the opponents, while paying to him three times the amount of coins than a normal Boo would do. Characters can ask for him only in night time; in daytime, Big Boo appears as a giant Boo statue. In Mario Party 4, Big Boo reappears in the board Boo's Haunted Bash. In the game, it appears in an odd blue color.
Game & Watch GalleryEdit
Big Boo is an opponent in the Boxing game for Game & Watch Gallery 4. He is Luigi's second opponent. However, instead of boxing gloves, Big Boo uses smaller Boos to pummel his opponents.
Paper Mario:TTYD and Super Paper MarioEdit
Big Boos have appeared in Paper Mario: The Thousand-Year Door and Super Paper Mario as a rare enemy. In the former, it is an optional boss. Rather than being called Big Boos, however, they are known as Atomic Boos, which is closer to their Japanese name (Atomic Teresa). In these games, it is confirmed that Big Boos / Atomic Boos may be larger because they are several Boo spirits combined.
New Super Mario Bros. WiiEdit
Big Boos reappear in the game New Super Mario Bros. Wii, and act much like they did in Super Mario World. They can only be encountered in Ghost Houses and are usually seen with a lot of smaller Boos.