Halfdan the Valiant (Hálfdan snjalli) (7th century) was the legendary father of Ivar Vidfamne according to Hervarar saga, the Ynglinga saga, Njal's Saga and Hversu Noregr byggdist. The genealogical work Hversu Noregr byggdist gives his father as Harald the Old, his grandfather as Valdar and his great-grandfather as Hróarr (i.e. the Hroðgar of Beowulf).
Ynglinga saga
Snorri Sturluson related that the Swedish king Ingjald Ill-ruler married his daughter Åsa to king Guðröðr of Scania. Åsa was her father's daughter and made Guðröðr murder his own brother Halfdan, the father of Ivar Vidfamne. Later, she was the cause behind Guðröðr's death as well, and had to escape back to her father. People afterwards called her Åsa Ill-ruler like her father Ingjald.
Ivar Vidfamne mustered a large army and besieged Ingjald and his daughter at Ræning, whereupon the two committed suicide by burning themselves to death inside the hall.
Hervarar saga
Whereas Hversu and Ynglinga saga don't inform about Halfdan's mother, Hervarar saga provides the information that she was Hild, the daughter of the Gothic king Heiðrekr Ulfhamr, the son of Angantyr who defeated the Huns.[citation needed]
It then tells that Halfdan had the son Ivar Vidfamne, who attacked Ingjald Ill-ruler, which led to Ingjald's suicide by burning down his own hall at Ræning together with all his retinue. After this, Ivar Vidfamne conquered Sweden.
Child(ren):