A linnorm is a high-powered dragon halfway between a lindwyrm and Fafnir. They are ancient, ill-tempered, and rumored to be the progentiors of all the draconic races.
I personally did a jabberwocky. There's also one on the Creature Collection page. There's also also one in the Munchkin d20 Munchkin's Monster Manual, and also also also one in some fey-based book whose name I cannot recall. And the Monsternomicon has a very well done version of the tatzlwyrm.
Demiurge out.