J is for Jormungandr
Fathered by Loki, the gargantuan sea serpent Jormungandr has a pretty important role in Norse mythology - or at least will eventually - as Jormy's role hasn't happened yet. You see at Ragnarok, the epic serpent is destined to bust onto the scene and cause all sorts of problems like spreading clouds of poison, steal library books, etc. It will culminate in one last head-to-head fight with Thor - they will trade body blows until Jormungandr will finally be slain. Unfortunately, Thor will then drown in the sea serpent's venom. Booyah!