Who is Cetus in Norse mythology?

I'm curious to learn more about Norse mythology and have a question regarding a lesser-known figure. Who is Cetus, and what role does he play in the grand tapestry of Norse legends? Is he a fearsome sea monster, a benevolent deity, or perhaps a minor figure with an intriguing backstory? I'm eager to delve into the depths of Norse mythology and uncover the mystery surrounding this enigmatic character.