Halfdan Haraldsson or Halfdan the Black was a son of Harald I of Norway by his first wife, Åsa, the daughter of Jarl Håkon Grjotgardsson of Lade. He was made sub-king of the Trondelag by his father, along with his brother Halfdan the White. According to Heimskringla, Halfdan the Black was poisoned, possibly at the behest of his sister in law Gunnhild, Mother of Kings.

References

• Driscoll, Matthew J. (1995). Ágrip af Nóregskonungasǫgum a Twelfth-Century Synoptic History of the Kings of Norway. London: Viking Society for Northern Research. ISBN 0-903521-27-X.
• Finlay, Alison (2003). Fargrskinna, a Catalogue of the Kings of Norway: a Translation with Introduction and Notes. Boston: Brill Academic Publishers. ISBN 90-04-13172-8.
• Sturluson, Snorri (1964). Heimskringla: History of the Kings of Norway. trans. Lee M. Hollander. Austin: Published for the American-Scandinavian Foundation by the University of Texas Press. ISBN 0-292-73061-6.
• Theodoricus monachus; Foote, Peter (1998). Historia De Antiquitate Regum Norwagiensuim. London: Viking Society for Northern Research, University College London. ISBN 0-903521-40-7.