Goob

Goobs are blue ghosts in Luigi's Mansion 3. They are the most common ghosts in the game, as well as the first ghosts to be fought. Behaving mischievously and punching to attack, they are the successor to Greenies from Luigi's Mansion: Dark Moon. Goobs may also perform a whirling spin attack. Each Goob has 100 HP.

Like Greenies, Goobs can also use weapons and objects to defend themselves, such as sunglasses and shields, which can be vacuumed away or pulled away with a Suction Shot. There are also Golden Goobs similar to Gold Greenies which drop more treasure, as well as another variety that drops a gem when defeated. There are also smaller variants called Mini Goobs which appear in hordes and can be sucked up quickly.

At the start of the game, when Luigi enters the Grand Lobby, there are Goobs disguised as humans. These ghosts are seen later on in their true form the next time Luigi enters the lobby, boarding up the front doors to prevent him from escaping. Goobs are encountered normally throughout the game, usually in groups of two or more.

Special Goobs with unique behaviors appear on certain floors and in boss fights.
 * Amadeus Wolfgeist summons ballet-dancing Goobs wearing tutus and Strobulb-blocking masks for the second part of his battle. These Goobs attack by pirouetting into Luigi and cannot be stunned until their masks are removed; once all of them are defeated, Amadeus will possess his piano and begin attacking Luigi personally.
 * In Castle MacFrights on the Coliseum Balcony, a pair of Goobs with trumpets play a fanfare for King MacFrights' introduction and when King MacFrights dares Luigi to reach him through his castle, the Goobs play their trumpets again. In the castle, Goobs with a sword or shield try to attack Luigi.
 * During the boss fight in Paranormal Productions, Morty films Luigi battling a Goob wearing the upper body of a kaiju suit. The suit enables the Goob to breathe various types of fireballs and expel hot breath, but once it's destroyed, the ghost behaves identically to a regular Goob.
 * While floating through the flooded sewers in the Boilerworks, scuba-diving Goobs posing as sharks will swim through the water in an attempt to pop Luigi's inner tube. They cannot be stunned or sucked up in this state. Once Luigi lowers the water level, these Goobs can be found floundering helplessly on the sewer floor. By removing their goggles, Luigi can flash them with the Strobulb and battle them as usual.
 * In the Central Chamber of the pyramid in Tomb Suites, mummies may emerge from sarcophagi lining the room to stagger after Luigi. Once their wrappings are unraveled, many of these mummies are revealed to be Goobs or Slinkers, which then proceed to attack as normal.
 * The first phase of DJ Phantasmagloria's boss fight has Luigi attempting to reclaim the Master Suite's elevator button from an octet of Goobs dressed like breakdancers, capable of attacking with various dance moves and passing the button amongst each other. Once the ghost carrying the button is sucked up, the rest of them disappear as Phantasmagloria reclaims the button and attacks Luigi herself; the remaining Goobs are fought later, but they act as normal Goobs.

The end of the game reveals the Goobs were being brainwashed by King Boo, as they and the other ghosts become social once the jewel from King Boo's crown soon vanishes from Luigi's hands as they were about to attack him. Among the rest of the game's standard ghosts (save for Trappers), Goobs are seen working with the protagonists to rebuild the fallen hotel through a series of pictures presented during the closing credits.

Hotel

 * Golden Goob
 * Gem Goob
 * Mini Goob
 * Boss Fights
 * Ballerina
 * Kaiju Suit
 * Breakdancer
 * Armed and Shielded
 * Sunglasses
 * Firefighter (Paranormal Productions / The Spectral Catch)
 * Cowboy (Paranormal Productions) / (Hotel Shops)
 * Shark (Boilerworks / (The Spectral Catch)
 * Mummies (Tomb Suites) / (Master Suite)
 * Feather Duster (RIP Suites)
 * Baguette (Mezzanine)
 * Donut (Mezzanine)
 * Sword (Castle MacFrights) / (Paranormal Productions) / (Twisted Suites)
 * Shield (Castle MacFrights) / (Paranormal Productions)
 * Strobe Flower (Garden Suites)
 * Lobster (Paranormal Productions)
 * Buckethead (Boilerworks)
 * Wrench (Boilerworks)
 * Plunger (Boilerworks)
 * Stone Dice (Twisted Suites)
 * Book (Twisted Suites)
 * Plate (Twisted Suites)
 * Baseball Bat (Fitness Center)
 * Dumbbells (Fitness Center)
 * Golf Club
 * Baseball Hat
 * Flashlight
 * Broom

ScareScraper

 * Gold Goob
 * Speed Goob
 * Bomb Goob
 * Regen Goob
 * Lethal Goob
 * Medic Goob
 * Diffusing Goob
 * Armed and Shielded
 * Hammer
 * Broom
 * Backpack
 * Mummies (Tomb Suites-themed Floors)

Themed variants
Each variant has 200 HP instead of 100. Otherwise, they are the same as regular Goobs; the only difference is the design and clothing, which does not affect their powers.

Agoobis
Appearing on Tomb Suites Scarescraper floors, Agoobises are Goobs decked in the regalia of ancient Egyptian royalty. Their name is derived from, the Egyptian god of the afterlife.

Sir Goob
Appearing on Castle MacFrights Scarescraper floors, Sir Goobs are Goobs outfitted in medieval knights' shining armor. Their name incorporates the formal term of address for a male knight.

Neon Goob
Appearing on The Dance Hall Scarescraper floors, Neon Goobs are Goobs decorated with glowing neon lights in jagged shapes.

Mergoob
Appearing on The Spectral Catch Scarescraper floors, Mergoobs are Goobs dressed as mermaids, wearing seashells and bearing scaly green patterns on their tails. Their name includes the prefix mer- denoting the sea and marine life.

Swabbie Goob
Appearing on The Spectral Catch Scarescraper floors, Swabbie Goobs are Goobs wearing the striped clothes of a sailor or buccaneer. Their name is based upon a nickname for a low-ranking crew member aboard ship.

Goob the Magnificent
Appearing on Twisted Suites Scarescraper floors, Goobs the Magnificent are Goobs attired in a magician's tuxedo. Their name is inspired by many magicians' self-laudatory stage names.

Pantogoob
Appearing on Twisted Suites Scarescraper floors, Pantogoobs are Goobs costumed as performing mimes, with white and red face makeup, dark striped shirts, and bright red neckerchieves. Their name is a portmanteau with pantomime, voiceless musical comedies popular in the 19th century.

Skelegoob
Appearing on Unnatural History Museum Scarescraper floors, Skelegoobs are Goobs draped in luminous skeleton garb.