His mother, Torny Gudbrandsdatter, was reportedly related to St. Olaf, the patron saint of Norway.

[3] Hallvard defended a pregnant woman, most likely a thrall, who had been given sanctuary from three men accusing her of theft.

Hallvard, however, was bound with a millstone around his neck, and the men attempted to sink his body in Drammensfjord but it refused to remain submerged, and as a result their crimes were discovered.

[4] St. Hallvard's Cathedral (Hallvardskatedralen) in Oslo was dedicated to his name and his remains were relocated to the facility which was finished in 1130.

[citation needed] The cathedral was built on the hill just north of the area that is now the Old Town market square in Oslo (intersection of Bispegata –Oslo gate).