Jovinus was a Gallo-Roman senator and claimed to be Roman Emperor (411–413 AD).
Following the defeat of the usurper known as Constantine III, Jovinus was proclaimed emperor at Mainz in 411, a puppet supported by Gundahar, king of the Burgundians, and Goar, king of the Alans. Jovinus kept his position in Gaul for two years, long enough to issue coinage that showed him wearing the imperial diadem. He was supported by a number of local Gallo-Roman nobles who had survived Constantine's defeat.
Gundaharius or Gundahar (died 437), better known by his legendary names Gunther (Middle High German: Gunther) or Gunnar (Old Norse: Gunnarr), was a historical King of the Burgundians in the early 5th century. Gundahar is attested as ruling his people shortly after they crossed the Rhine into Roman Gaul. He was involved in the campaigns of the failed Roman usurper Jovinus before the latter's defeat, after which he was settled on the left bank of the Rhine as a Roman ally. In 436, Gundahar launched an attack from his kingdom on the Roman province of Belgica Prima. He was defeated by the Roman general Flavius Aetius, who destroyed Gundahar's kingdom with the help of Hunnish mercenaries the following year, resulting in Gundahar's death.
The historical Gundahar's death became the basis for a tradition in Germanic heroic legend in which the legendary Gunther met his death at the court of Attila the Hun (Etzel/Atli). The character also became attached to other legends: most notably he is associated with Siegfried/Sigurd and Brunhild, and is implicated in Sigurd's murder. He also appears as an adversary in the legend of Walter of Aquitaine. It is generally assumed that Gunther's involvement in these other legends, in which he plays a secondary or antagonistic role, is a later development. Gunther's importance in the story of the destruction of the Burgundians also waned with time.