Jormungandr

Jormungandr, the Midgard Serpent, is another child of Loki, cast into the sea by Odin, where it grew until it encircled the whole world and could bite its own tail. Its stories are all encounters with Thor. In one, Thor goes fishing with the giant Hymir, baits his line with an ox-head, and hauls the serpent to the surface, raising his hammer to strike, but Hymir, in terror, cuts the line, and the blow is lost; the scene is among the most frequently depicted in Norse art, appearing on picture-stones and carvings.

In another, at Utgarda-Loki's hall, Thor is tricked into trying to lift the serpent, disguised as a great grey cat, and manages only to raise one paw. Their final meeting is at Ragnarok, where Thor kills the serpent but staggers nine steps from its venom and falls dead. The world-encircling serpent biting its tail is sometimes compared to the ouroboros of Mediterranean tradition, though the Norse figure is a specific mortal adversary rather than a symbol of eternity.

The world serpent exists to be Thor's opposite number, and the sources stage the meeting three times. In the first, Thor goes fishing with the giant Hymir using an ox head for bait, hooks the serpent, and hauls it up until they are face to face. Hymir, terrified, cuts the line. The scene was popular enough to be carved on stones and it is one of the few episodes attested in both the poetry and the prose.

The second is a disguise. At the hall of Utgarda-Loki, Thor is challenged to lift a grey cat and manages only to raise one paw from the floor. Afterwards his host admits the cat was the serpent, that the company watched in horror as one end of the world came loose, and that Thor was tricked into a contest he could not be allowed to win. The passage is comedy that turns cold in its last lines.

The third is the end. At Ragnarok they kill each other: Thor strikes the serpent down, walks nine paces, and falls dead from its venom. The number nine recurs throughout the corpus and the count is deliberate. Taken together the three meetings make an argument that the poems never state directly, which is that the strongest of the gods and the thing that encircles the world are held in balance until they are not.