Hagbard, 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.

Karl Werner Lothar Koch (born July 22, 1965 in Hanover, died - probably - May 23, 1989) was a German hacker in the 1980s, who called himself "hagbard", after Hagbard Celine. He was involved in a cold war computer espionage incident.