Cetus

The Cetus is an enormous sea monster from Greek myth. It was thought to be owned by Posiedon and possibly created by Zeus. It was made to kill princess Andromeda. She was chained to a rock to be fed to the Cetus because her mother bragged about her beauty and insulted the goddesses and nymphs. It ended up being turned to stone by Perseus by use of the head of Medusa. It had a giant body like a bloated whale or dolphin, with a tail divided into two fan-like sections. It was colored brownish-yellow and turquoise with no limbs other than vestigial membranous flippers on its torso. It had a fiery red crest surrounding its head, a head like a greyhound, and walrus tusks.

Citations:

Rose, Carol. Giants Monsters and Dragons: An Encyclopedia Of Folklore Legend And Myth. United Kingdom, WW Norton, 2001.

Zell-Ravenheart, Oberon, and DeKirk, Ashley. Dragonlore: From the Archives of the Grey School of Wizardry. United States, Red Wheel Weiser, 2006.