Niflungr

The term Niflungr (Old Norse) or Nibelung (German) is a personal or clan name with several competing and contradictory uses in Germanic heroic legend. It has an unclear etymology, but is often connected to the root nebel, meaning mist. The term in its various meanings gives its name to the Middle High German heroic epic the Nibelungenlied.

The most widespread use of Niflungr is used to denote the Burgundian royal house, also known as the  Gjúkingar (Old Norse) or Gibichungs (German). A group of royal brothers led by king Gunnarr/Gunther, the Gjúkingar are responsible for the death of the hero Sigurðr/Siegfried and are later destroyed at the court of Attila the Hun (Atli/Etzel). This is the only use of the term attested in the Old Norse legends.

Waltharius
The earliest probable surviving mention of the name is in the Latin poem Waltharius, believed to have been composed around the year 920. In lines 555–6 of that poem Walter, seeing Guntharius (Gunnarr) and his men approaching says (in the Chronicon Novaliciense text, usually taken to be the oldest):

The translation is: "These are not Avars, but Frankish Nivilons, inhabitants of the region." The other texts have nebulones 'worthless fellows' instead of nivilones, a reasonable replacement for an obscure proper name. In medieval Latin names, b and v often interchange, so Nivilones is a reasonable Latinization of Germanic Nibilungos. This is the only text to connect the Nibelungs with Franks. Since Burgundy was conquered by the Franks in 534, Burgundians could loosely be considered Franks of a kind and confused with them. The name Nibelunc became a Frankish personal name in the 8th and 9th centuries, at least among the descendants of Childebrand I (who died in 752 ). Yet, in this poem, the center of Gunther's supposedly Frankish kingdom is the city of Worms on the Rhine.

Norse attestation
In the eddic poem (see Poetic Edda) Atlakviða, the word Niflungar is applied three times to the treasure (arfr) or hoard (hodd) of Gunnarr. It is also applied once to Gunnarr's warriors and once to Gunnarr himself. It elsewhere appears unambiguously as the name of the lineage to which the brothers Gunnarr and Hǫgni belong and seems mostly interchangeable with Gjúkingar or Gjúkungar, meaning descendants of Gjúki, Gjúki being Gunnarr's father.

The variant form Hniflungr also occurs as the name of Högni's son in the eddic poem Atlamál, and as a term for the children born by Gunnarr's sister Guðrún to Atli. It appears to be a general term for "warrior" in Helgakviða Hundingsbana I. Hniflungar might be of separate origin, meaning descendants of Hnef, referring to the Hnæf son of Hoc who is prominent in the Old English Finnesburg Fragment. However h was early dropped initially before other consonants in Norwegian dialects which might have led to the adding of h to names in other dialects where it did not originally belong.