Norse dragon

In Norse mythology there are several references to dragons.

In the Völuspá the being Níðhöggr is identified as a dragon (Old Norse: dreki).
The Midgard Serpent is described as a giant, venomous serpent.
So is Fáfnir in the Volsung cycle in the Poetic Edda.
The Gesta Danorum contains a description of a dragon killed by Frotho I.