Gundoald or Gundovald was a Merovingian usurper king in the area of southern Gaul in either 584 or 585. He claimed to be an illegitimate son of Clotaire I and, with the financial support of the Emperor Maurice, took some major cities in southern Gaul, such as Poitiers and Toulouse, which belonged to Guntram, king of Burgundy, a legitimate son of Clotaire. Guntram marched against him, calling him nothing more than a miller's son and named him 'Ballomer'. Gundowald fled to Comminges and Guntram's army set down to besiege the citadel (now known as Saint-Bertrand-de-Comminges). The siege was successful, Gundovald's support drained away quickly and he was handed over by the besieged to be executed.
The sole source for Gundovald is Gregory of Tours, who wrote about the events in his 'Histories', books 6 and 7. Gundovald was never king of Aquitaine as is sometimes thought; there was no such separate kingdom at the time. While his main backers were magnates of Austrasia, the Byzantine support consisted of treasure to buy followers and it is probable that Gundovald spent time in Constantinople before setting off to conquer parts of Gaul.
The usage of 'ballomer', a Frankish (possibly offensive) word of which the meaning is not known, is one of the first instances of the mentioning of a Germanic word in a literary source.