Gormungandr

Gormungandr, Serpent of Arreat is a unique Rockworm (of Demonic Serpent subtype) that can spawn in Arreat Crater Level 1 in of Diablo III.

It has the Frozen Pulse, Frozen and Plagued affixes.

Trivia
The name of the creature is a reference to the World Serpent Jörmungandr in Norse mythology.