Nidhogg is a playable dragon in Dragalia Lost.

Official Description

A dragon that rules over death. It's not so much that he enjoys murder, but he does thrive off the strong emotions of the doomed. As such, he appears in times of plague, war, and disaster, making him much feared as an ill omen.

Official Description (Gala Reborn Nidhogg)

Nidhogg, wicked wyrm with dominion over death itself, reborn into a new form. Freed from wicked miasma by a maiden's determination, he takes a newfound interest in humanity—not just in their ends, as before, but now in their lives as well.