|Main Weapon||claws and teeth|
|First Appearance|| Volume 2 (Ragnarok)|
Episode 14 (Ragnarok Online)
|“||May the blessing of Mother Yggdrasil be with you...||”|
Nidhoggr is the devourer of the dead and the most terrible of all dragons. She is ever chewing at the roots of Yggdrasil, the tree of life. She is the mortality of the world and a sign of its coming demise.
On iRO, this character is localized as Nidhoggur.
It is discovered that Frigg's existence is bound to Nidhoggr and the dragon's summoning allowed Frigg to reach out to Chaos and the others after Payon's destruction. In addition, Nidhoggr had also been tasked to guard Yggdrasil, the great tree that binds all realms together.
After Surt was sealed by Thanatos, he managed to relay whispers to Nidhoggr, causing her to become confused and lost in her loneliness. When she at last sealed herself off from everything, Bifrost was torn asunder, its crack engulfed in a Forest of Mist. It wasn't until Loki and a lone adventurer sought her out that Nidhoggr regained herself and realized that she was being manipulated by Surt.
Some time later, Loki and Nidhoggr make their way to Eclage where they discover that the adventurer they met before has been thrown in prison for attacking the Laphine soldiers there. They tell Minuel that they don't believe the adventurer could ever do a thing and the Laphine agrees to take the adventurer to the clinic for them to confirm their beliefs. In the clinic, Loki reveals that the adventurer had been inflicted with a thorn that caused him/her to hallucinate the Laphine soldiers as incarnations of Surt. Loki goes on to reveal that Shenime herself has been manipulated by an incarnation of Surt that is able to control others through a part of its body. Nidhoggr also agrees with Loki that the adventurer would never do a thing like that if he/she was fully aware of his/her surroundings. Unfortunately, someone needed to take responsibility and Loki admits that person has to be the adventurer. Hisie wonders what Loki and Nidhoggr will do now and Loki explains that they've been trying to track down Surt and that this latest clue will help them.
Nidhoggr and Loki eventually track down Surt with the help of the adventurer and chase after him to put an end to the demon god's reign of terror.