Goblin

Goblin (ゴブリン), also known as Air Tikki in the Mega Man 2 instruction manual for the U.S., is an indestructible giant goblin head that appears in Air Man's stage. Its horns lift slowly and periodically to damage enemies, and if an enemy stays on its head, it will use small versions of himself (Petit Goblin, see below) to remove them. It was originally used in a robot circus. The Time Stopper is a good weapon to use on it, as it will prevent its horns from rising and it won't release Petit Goblins, making passage across them easier.

Petit Goblin
Petit Goblin (プチゴブリン), also known as Gremlin in the Mega Man 2 instruction manual for the U.S., is a small Goblin that appears from the ears of a Goblin when an enemy stands on his head. They are a good way to win items, if the player stays on the head of the Goblin using Leaf Shield. It is called "Puti Goblin" in Mega Man II.

Other media
Goblin and Petit Goblin had a short appeareance in issues 10 and 11 of the Mega Man comic series by Archie Comics, in Mega Man Megamix, and in Rockman: Dr. Wily no Inbou.

Trivia

 * Petit is French for "small".
 * In page 366 of the book R20+5 Rockman & Rockman X Official Complete Works, there is a concept of a Mega Man 10 sub-boss consisting of a double-faced Goblin combined with Kaminari Goro, Kaminari Kogoro and Oni Robo. It appears to release Petit Goblins from only one ear.