From the Super Mario Wiki
“Gringills like those could gobble us all up in one bite!”
—Penguin, Super Mario Galaxy
Gringills are large, orange or lavender eel-like creatures with large eyes and teeth found in Super Mario Galaxy. Their name is a portmanteau on "grin" and "gill".
They first appear in the Beach Bowl Galaxy and later appear in the Drip Drop Galaxy, Sea Slide Galaxy, Bigmouth Galaxy, and Deep Dark Galaxy. They attack simply by trying to bite Mario. Gringills can be defeated by throwing a Koopa Shell at them while they are underwater. Gringills may be the Super Mario Galaxy equivalent of Unagi. Most of them appear in caves, and they come out a small distance when Mario/Luigi gets close, though rarely they are seen outside their holes, swimming in circles. There are also huge Gringills that are lavender in colour, have two feelers on their lower jaws, and are found only in caves. They make a straining noise when coming out of their holes, and give a 1-Up Mushroom when defeated. These huge eels only appear in the Beach Bowl Galaxy, Sea Slide Galaxy, and Deep Dark Galaxy.
They reappear in Super Mario Galaxy 2 in the Cosmic Cove Galaxy, the Starshine Beach Galaxy, and the Slimy Spring Galaxy, behaving like they did in the previous game.
Names in other languages
|From 「穴子」 anago, meaning "sea eel".
||From the Japanese name