Gearmos are robots that appear in Super Mario Galaxy and Super Mario Galaxy 2. They are usually seen in industrialized galaxies, and are pictured as friendly maintenance robots that often advise Mario. Their name could be a portmanteau of the words "gear" and "ammo".
 Super Mario Galaxy
Gearmos make their first appearance in Super Mario Galaxy.
A green Gearmo appears in the Engine Room of the Comet Observatory, being the only NPC other than Polari in a dome.
Two similar-looking green Gearmos appear in the ammo depots in the Battlerock Galaxy and in the Dreadnought Galaxy. They both hold a metal stick with a magnet attached to the end of it, and ask Mario if he wants to blow up trash with bombs. If Mario manages to destroy all the garbage within the time limit, they will reward him with a [Power Star]].
 Super Mario Galaxy 2
Gearmos return in the sequel, Super Mario Galaxy 2 once again with the purpose of maintaining the various galaxies they appear in. The main galaxy they appear in is the Chompworks Galaxy where they are responsible for breaking open Chomps.
Similar to the missions with the Bob-ombs in the original, two Gearmos with magnet sticks appear once again in the Rightside Down Galaxy and the Upside Dizzy Galaxy but this time they give Mario a Fire Flower and ask Fire Mario to burn up all the crates in twenty seconds or less in the Crate Burning mini-game.
Later, two Gearmos appear in the Tall Trunk Galaxy's Prankster Comet mission. One at the top of the slide claims to have lost 140 Purple Coins and asks Mario to get them for him. He tells them that her buddy at the bottom will give him a prize if he does. And, true to her word, the Gearmo at the bottom of the slide will give Mario a Power Star if he got at least 100 Purple Coins. A green Gearmo also appears in Rolling Coaster Galaxy's Prankster Comet, giving Mario the star if he succeeds in getting the 100 Purple Coins.
When special missions are completed in the Boulder Bowl Galaxy and Space Storm Galaxy, two Gearmos, a Gold Gearmo and a Silver Gearmo, will join Mario in his adventures on Starship Mario, and give him a 1-Up Mushroom when talked to. This is similar to the garbage challenge from the prequel, with the Gearmos all being green.
In this game, when hit with Star Bits or spun at, their heads spin around.
 Characteristics and traits
Most Gearmos are irritable neat-freaks. The Gearmo with the magnet becomes furious at Mario if he does not complete the Bob-omb Challenge. Another one gets angry at him for destroying a giant weight holding down a tower, and another warns Mario not to let it catch him littering.
Gearmos have a large gear inside the back of their heads. If Mario jumps on the gear, it pops out, and falls back into place. Gearmos are capable of moving without the gear, suggesting that the gear has no real purpose. This may also indicate that Gearmos are living beings rather than robots. Further proof of this is the fact that, if the player gets zero purple coins in the Battlerock Galaxy, the Gearmo at the end will refer to herself as "this old iron lady", indicating Gearmos have separate genders, despite being iron robots. Some Gearmos are also shown to possess immense strength, such as the ability to destroy Chomps with bare hands.
 Manner of speaking
 Names in Other Languages