Octar or Ouptaros was a Hunnic ruler. He ruled in dual kingship with his brother Rugila, possibly with a geographical division, ruling the Western Huns while his brother ruled the Eastern Huns.

The name is recorded in two variants, Greek Ούπταρος (Ouptaros), and Latin Octar.^[1] The change from -ct- to -pt- is characteristic of Balkan Latin.^[1][2] Otto J. Maenchen-Helfen considered the name to be of unknown origin.^[3] Omeljan Pritsak derived the name from Turko-Mongolic word *öktem (strong, brave, imperious; proud, boastful; pride) and verb ökte- / oktä- (to encourage).^[1] He argued that the deverbal Turkic-Mongolian suffix m was replaced in Turkic by z while in Mongolian by ri.^[1] The reconstructed form is appellative *öktä-r.^[1]

Octar ruled along with his brother Rugila as reported by Jordanes in his Getica: "...Mundzucus, whose brothers were Octar and Ruas, who were supposed to have been kings before Attila, although not altogether of the same [territories] as he".^[4] Their brother Mundzuk was the father of Attila, but he was not a supreme ruler of the Huns.^[4] According to Priscus their fourth brother Oebarsius was still alive in 448 AD.^[4] Their ancestors and relation with previous rulers Uldin and Charaton are unknown.^[5]

He ruled with his brother in dual kingship, possibly a geographical division where Rugila ruled over Eastern Huns while Octar over Western Huns, possibly like Attila and Bleda.^[6]

According to Socrates of Constantinople, Octar, identified with Ouptaros, died in 430 near the Rhine, "[f]or the king of the Huns, Uptaros by name, having burst asunder in the night from surfeit, the Burgundians attacked that [the Huns of Uptaros] people then without a leader; and although few in numbers and their opponents many, they obtained victory".^[7]