Fenris was a giant Asgardian Wolf who served Hela during the times of the expansion of Asgard around the Nine Realms. Millennia after her death, Fenris was resurrected by Hela with the Eternal Flame and put at her service during her rule over Asgard.

What's the wolf's name in Ragnarok?

Fenrir, also called Fenrisúlfr, monstrous wolf of Norse mythology. He was the son of the demoniac god Loki and a giantess, Angerboda.

Why is Fenrir called Fenris Wolf?

He is also known as the Fenris Wolf (also given as Fenris-wolf) and Vanargand (“monster of van”) usually understood to mean “creature of expectation” because he was prophesied to participate in the destruction of the gods. His name is pronounced Fen-rear, and he was born of the union of Loki and the giantess Angrboda.