Ymir (Earth-6531)

"Did you truly think you could harm me, Odinson? I am one of the ancients. Endless. Eternal. You are far from home. This is MY domain, and here you will fall..."

- - Ymir to Thor

Ymir was the first and most powerful of all Frost Giant, being imprisoned in Niflheim millennia in the past, even before Laufey surrendered to Odin and declared uneasy peace.

Biography
In the hopes of appearing fit to be the ruler of Asgard, Loki ventured to Niflheim and resurrected the frozen body of Ymir. As Ymir wanted to take the Casket of Ancient Winters, he accepted to help the God of Mischief.