Hagbard (Old Norse Hagbarðr), the brother of Haki and son of Hamund, was a famous Scandinavian sea-king in Norse mythology. He is mentioned in Skáldskaparmál, Ynglinga saga, Nafnaþulur, Völsunga saga and Gesta Danorum. The heroes' connections with other legendary characters place the events in the 5th century AD.
Hagbard remained well-known until recent times in the legend of Hagbard and Signy. This famous legend tells that Hagbard fell in love with Signy, the daughter of king Sigar, the nephew of king Siggeir (of the Völsunga saga), a love affair which ended in their deaths, when Sigar wanted to have Hagbard hanged. This legend is told most fully in Gesta Danorum (book 7).
However, most legends surrounding Hagbard are probably lost. In the Völsunga saga, Gudrun and Brynhild have a discussion on the "greatest of men" referring to a legend now lost, where Hagbard is mentioned together with Haki's sons, who have not yet avenged their sisters by killing the evil Sigar (the feud with Sigar is still going on and Hagbard not yet hanged):
"Good talk," says Gudrun, "let us do even so; what kings deemest thou to have been the first of all men?" Brynhild says, "The sons of Haki, and Hagbard withal; they brought to pass many a deed of fame in the warfare." Gudrun answers, "Great men certes, and of noble fame! Yet Sigar took their one sister, and burned the other, house and all; and they may be called slow to revenge the deed; why didst thou not name my brethren who are held to be the first of men as at this time?"
"Hagbard's gallows", a megalithic monument in Asige, Halland, Sweden.