Jörmungandr

Loki had three Children with Angrboða, and their children have been sometimes considered monsters. One of these children was a serpent called Jörmungandr. This Midgard serpent was the middle child, born after Fenrir and before Hel. When these three were still relatively small, Odin received a prophesy from the Völva, saying each of them would have a role to play at Ragnarök.

To prevent this, Odin removed the problem. Jörmungandr was prophesized to bring about the end of Thor, so Odin threw the serpent into the sea. Again, at the time, Jörmungandr was still small enough for Odin to do so. But in the sea, the serpent grew. His body became large enough to cause not just ripples, but giant waves as he swam. But Jörmungandr couldn't swim far for long, because he grew so large he had wrapped himself around the entire earth. And at that size in such a tiny space as the ocean, and having not enough to eat, as he was so large nothing could satisfy his hunger, Jörmungandr began to eat at his own tail. Like a big hungry dog trapped inside a tiny cage, he ate and ate and grew bigger and bigger.