Giselher was a king of Burgundy in the Nibelungenlied, brother to kings Gunther and Gundomar I (also called Gernot).
Historically, these correspond to three sons of king Gebicca, Gundomar, Gislaharius (Giselher) and Gundaharius (Gunther), who ruled the Burgundians in the 410s.
In the Nibelungenlied, he is betrothed to Dietlind, the daughter of Count Rüdiger of Bechelaren.
He was likely the second son of Gebicca, not the third as is reported in the Nibelungenlied.
He was succeeded by his brother Gundaharius.