The Imperial County of Ortenburg was a state of the Holy Roman Empire in present-day Lower Bavaria, Germany. It was located on the lands around Ortenburg Castle, about 10 km (6 mi) west of Passau. Though the Counts of Ortenburg—formerly Ortenberg—emerged in the 12th century as a cadet branch of the Rhenish House of Sponheim (Spanheim) who then ruled over the Duchy of Carinthia, an affiliation with the Carinthian Ortenburger comital family is unverifiable.

The House of Sponheim or Spanheim was a medieval German noble family, which originated in Rhenish Franconia. They were immediate Counts of Sponheim until 1437 and Dukes of Carinthia from 1122 until 1269. Its cadet branches ruled in the Imperial County of Ortenburg-Neuortenburg and various Sayn-Wittgenstein states until 1806.