Halfdan the Old (Old Norse: Hálfdanr gamli and Hálfdanr inn gamli) was an ancient, legendary king from whom descended many of the most notable lineages of legend. A second Halfdan the Old is the purported great-grandfather of Ragnvald Eysteinsson.
Halfdan and his sons
The Ættartolur, the genealogies appended to the Hversu Noregr byggdist in the Flatey Book introduce Halfdan the Old as the ruler of Ringiríki (a territory including modern Ringerike and Valdres in Oppland). Halfdan is here the son of King Hring (eponym of Ringeríki) by the daughter of a sea-king named Vífil (Vífill). Hring was son of Raum the Old (eponym of Raumaríki) by Hild (Hildr) the daughter Gudröd the Old (Guðrǫðr inn gamli). Raum the Old was son of Nór (Nórr) (the eponym of Norway). See Nór for further details about Nór and his ancestry and descendants.
In his sacrifice Halfdan requested a lifetime of 300 years like that of his ancestor Snær. The form Tiggi appears instead of Tyggi in the list of the first nine sons. The list of the second nine sons has Skelfir instead of Yngvi and the form Næfil (Næfill) instead of Nefir. The order of the names is the same and it is explained that Hildir, Sigar, and Lofdi were war-kings; Audi, Budli, and Næfil were sea-kings, while Dag, Skelfir, and Bragi remained on their lands.
Dag married Thóra Heroes-mother (Thóra drengjamóður) who bore him nine sons, but only four are named: Óli, Ám (Ámr), Jöfur, and Arngrím (Arngrímr).
Óli was father of Dag, father of Óleif (Óleifr), father of Hring, father of Helgi, father of Sigurd Hart (Sigurðr Hjǫrtr), father of Ragnhild (Ragnhildr) the mother of Harald Fairhair.
Arngrím married Eyfura who bore him Angantýr the Berserk (Angantýr berserkr). Angantýr's story is most fully treated in the Hervarar saga. It also appears in part in book five of Saxo Grammaticus' Gesta Danorum and an account only the deaths of Angantýr and his eleven brothers appears in Arrow-Odd's saga.
Stanza 18 of the Hyndluljód reads:
The mate of Dag was a mother of heroes [drengja móður],
Thóra, who bore him the bravest of fighters,
Fradmar [Fraðmarr] and Gyrd [Gyrðr] and the Frekis [Frekar] twain,
Ám and Jöfurmar [Jǫfurmar], Álf the Old;
It is much to know,— wilt thou hear yet more?
The name Ám agrees with that of a son of Dag in the Ættartolur and Jöfurmar is probably identical with Jöfur of the Ættartolur. Fradmar, Gyrd, Álf the Old, and the two Frekis bring the total to seven. Adding the names Óli and Arngrím to this list from the Ættartolur brings the tally to nine, as the Ættartolur promised. This may be coincidental. It is odd that the Hyndluljód here leaves out the only two names for which the Hversu provides descendants. It is possible that the following stanzas of the Hyndluljód down to stanza 24 cover otherwise unknown members of the Dögling lineage since stanza 23 at least returns to the Dödlings, providing the names of the twelve sons of Arngrím and the following stanza tells of their birth to Arngrím and Eyfura. Áli mentioned in stanza 14 of the Hyndluljód (quoted near the beginning of this article) may be identical to Óli son of Dag mentioned in the Ættartolur.