Níðhöggr
Nidhogg or Nidhug, who resides on one of the three branches of Yggdrasil (Old Norse: Níðhöggr; which can be translated as « the one who hits full of hate"), in Norse mythology (according to Völuspá), is a dragon that lives in Niflheim where one of the roots of the Yggdrasil tree grows, which it gnaws incessantly until it Ragnarök comes and everything is destroyed. After regeneration, Nidhogg will torment the human souls that have remained in Niflheim, feeding on the bodies of the deceased and the blood that he deposits in their skulls.
While living in the roots of Yggdrasil, Ratatösk runs up and down carrying the gossip between the nameless eagle and the falcon Veðrfölnir, both atop Yggdrasil, to Nidhogg, hoping to cause trouble between them.
Spelling
In the Old Norse standardization, the name is spelled Níðhǫggr or Niðhǫggr, but the letter ǫ is frequently replaced by Modern Icelandic ö for reasons of familiarity or technical convenience.
The name can be represented in English texts with i for í; th, d or (rarely) dh for ð; o for ǫ and optionally without r as in modern Scandinavian highlights. The modern Icelandic form Níðhöggur is also sometimes seen, with special characters or similarly anglicized. The Danish forms Nidhug and Nidhøg can also be found; o Norwegian Nidhogg and Swedish Nidhogg.
Symbols
While the suffix, -höggr, clearly means "hitter", the prefix is not so clear. In particular, the length of the first vowel is not determined in the original sources. Some scholars prefer the reading Niðhöggr (Thumper of the Night).