This list of mythical creatures that begin with this letter and I am constantly gathering information from each continent, and is continually being updated.
Jormungandr (Norse)
In Norse mythology, Jormungandr, also known as the Midgard Serpent or World Serpent, is an unfathomably large sea serpent or worm who dwells in the world sea, encircling the Earth (Midgard) and biting his own tail, an example of an ouroboros. As a result of it surrounding Midgard (the Earth) it is referred to as the World Serpent. When it releases its tail, Ragnarok (the final battle of the world) will begin.
While Jormungandr has the appearance of a mighty serpent, he is in fact a giant, son of the trickster Loki, who despite living alongside the Aesir gods in Asgard was a giant, and the giantess Angrboda, whose name means ‘bringer of anguish’ in old Norse. Jormungandr was brother to two further children of the giant couple, the giant wolf Fenrir, and the Underworld Goddess Hel. Odin was so fearful of the havoc that these beings might cause on the universe that he placed each of them somewhere that they could cause the least harm.