There is a lot of confusion over the origins of some of these tales and over time the lines blurred between Germanic and Scandinavian lore. If the story is not here, check Scandinavia.
Drachenfels is a dragon-shaped rock on the Rhine River.
According to the Anglo Saxon Chronicle of the 9th Century - a fiery dragon (comet?) in 793 was a sign of the impending Viking raid of the Lindisfarne monestary.
According to Craig Davis in "Cultural Historicity in the Battle of Maldon.", German heroes tend to be the product of embattled societies and are killed on the world's last day as they fight cosmic monsters. Examples include Beowulf and Thor.
The German word for dragon, "lindwurm", actually means "snake-worm" and demonstrates the confusion that language can have. Words originally intended to mean "serpent" have been used for dragon and vice versa. (Source: Survive 2012)
Zoracht in Old High German is related to and/or derived from the Greek work "spakov", meaning dragon. (Source: Survive 2012_