The giant wolf destined to devour Odin during Ragnarök is Fenrir.
Fenrir, also called Fenrisúlfr, is one of the most dangerous beings in Norse mythology. He is the son of the trickster god Loki and the giantess Angrboða, making him the sibling of the world-serpent Jörmungandr and Hel, ruler of the dead. The gods feared Fenrir’s growing strength and bound him with the magical fetter Gleipnir.
At Ragnarök, Fenrir breaks free and battles the gods. The wolf swallows Odin, but Odin’s son Víðarr avenges him by killing Fenrir. This event is often simplified in popular retellings, which may call Fenrir merely a monster; in the myths, he is also part of a prophetic family whose fate is tied to the destruction and renewal of the world.
Garmr, Geri, and Freki are different wolves or wolf-like figures. Geri and Freki are Odin’s companions, while Garmr is associated with the underworld and Ragnarök.