Balloon Boo

From the Super Mario Wiki

Not to be confused with Boo Balloon

A Balloon Boo in an early screenshot of New Super Mario Bros.

Balloon Boos are large relatives to Big Boos. They are small, and act like normal Boos, but if looked at, they will start sucking in air. The more air they suck in, the larger they get. If the player turns away from them, they will start to chase the player, letting out the air they sucked in in the process, and thus decreasing in size again.

Balloon Boos only appear in New Super Mario Bros., only in Ghost Houses.

Undead

Luigi's Mansion Ghosts

Characters
Neville \| Lydia \| Chauncey \| The Floating Whirlindas \| Shivers \| Melody Pianissima \| Mr. Luggs \| Spooky \| Bogmire \| Biff Atlas \| Miss Petunia \| Nana \| Slim Bankshot \| Henry and Orville \| Madame Clairvoya \| Boolossus \| Uncle Grimmly \| Clockwork Soldiers \| Sue Pea \| Jarvis \| Sir Weston \| Vincent Van Gore \| King Boo \| 50 Boos
Species
Bat \| Blue Blaze \| Blue Mouse \| Blue Twirler \| Bowling Ghost \| Ceiling Surprise \| Flash \| Flying Fish \| Garbage Can Ghost \| Grabbing Ghost Gold Ghost \| Gold Mouse \| Mr. Bones \| Purple Bomber \| Purple Mouse \| Purple Puncher \| Shy Guy \| Spark \| Speedy Spirit \| Temper Terror \| Waiter \| Bogmire Shadow \| Fire Elemental Ghost \| Ice Elemental Ghost \| Trapdoor \| Water Elemental Ghost

Other/Unknown

Species/Characters
???? \| Bink \| Blinky \| Bloat \| Bone Dragon \| Bonechill \| Boneheads \| Bonetail \| Bony Beetle \| Boo \| Bouldergeist \| Caged Ghost \| Captain Skull \| Cortez \| Count Zoltan Dracula \| Cractus \| D-Man \| Dangling Ghost \| Dark Skellobit \| Dark Spiky Skellobit \| Davy Bones \| Doopliss \| Doppel \| Dry Bowser \| Eerie \| Elvis Presley \| Ember \| Exterminator \| Fishbone \| Flightless Skeleton Goonie \| Frankenstein's Monster \| Ghost Barrel \| Ghost Glove \| Ghost Goom \| Ghost Piranha \| Ghost Rider \| Ghost Rope \| Ghosts of Christmas \| Ghost T. \| Ghoul Guy \| Giant Ghost \| Glum Reaper \| Goomba Mummy \| Gooey \| Greaper \| Grim Leecher \| Grindel \| Gusty \| Hector the Reflector \| Hobgoblin \| Honen \| Hoohoo Spirit \| Invisighoul \| Inviso \| Queen Jaydes \| Jean de Fillet \| Kackle \| Kingfin \| Kloak \| Krossbones \| Krow \| Lava Bubble \| Madam Merlar \| Mastadoom \| Merlumina \| Meteor Ghost \| Monsieur Boo \| Mummipokey \| Mummy Guy \| Pandorite \| Phantom Ember \| Phantom Guy \| Phantom Hand \| Pionpi \| Pokey Mummy \| Poobah the Pharaoh \| Queen Mushroomkhamen \| ReDead \| Reacher \| Resident Demon \| Roger the Potted Ghost \| Sarcopha Guy \| Shadow \| Shadow Queen \| Shayde \| Shiisa \| Skeleton Bee \| Skeleton Goonie \| Skellobait \| Skellobit \| Skellobomber \| Skellokey \| Slime Ghost \| Spiky Skellobait \| Spiky Skellobit \| Spindel \| Straw Head \| Support Ghost \| Three Musty Fears \| Tweeter Bat \| Underhand \| Wrinkly Kong \| Zombie Goomba \| Zombone

Boo Characters
Bigger Boo \| Boolossus \| Boos in Luigi's Mansion \| Bootler \| Franky \| Herbert \| Igor \| King Boo \| Lady Bow \| Lahla \| Peeka \| Spooky Speedster \| Stanley \| The Creepy Steeple Boo
Boos
Atomic Boo \| Balloon Boo \| Big Boo \| Big & Little Boo \| Blindfold Boo \| Bomb Boo \| Boo \| Boo Balloon \| Boo Buddy (SMW) \| Boo Buddy (YS) \| Boo Buddy Block \| Boo Buddy Snake \| Boo Guy \| Boo Man Bluff \| Broozer \| Calm Fishin' Boo \| Circling Boo Buddies \| Dark Boo \| Dark Dark Boo \| Disappearing Boo Buddies \| Fishin' Boo \| Li'l Boo \| Mad Big Boo \| Mad Boo \| Red Boo \| Sleepy Boo \| Stretch \| Terekuribo