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 the Old, ancestor of many lineages
Hyndluljód
The eddic poem Hyndluljód states in verses 14–16: "Of old the noblest of all was Áli, Before him Halfdan, foremost of Skjöldungs [Skjǫldungar]; Famed were the battles the hero fought, To the corners of heaven his deeds were carried. "Strengthened by Eymund [Eymundr], the strongest of men, Sigtrygg [Sigtryggr] he slew with the ice-cold sword; His bride was Álmveig [Álmveigr], the best of women, And eighteen boys did Álmveig bear him. "Hence come the Skjöldungs, hence the Skilfings, Hence the Ödlings [Ǫðlingar], hence the Ynglings, Hence come the free-born, hence the high-born, The noblest of men that in Midgard dwell: And all are thy kinsmen, Óttar, thou fool!"
Though Halfdan is himself called a Skjöldung in verse 14, in verse 16 the Skjöldungs are named instead as one of the families that sprang from Halfdan's marriage with Álmveig.
Skáldskaparmál
Snorri Sturluson explains in the Skáldskaparmál: There was a king named Halfdan the Old, who was most famous of all kings. He made a great sacrificial feast at mid-winter, and sacrificed to this end, that he might live three hundred years in his kingdom; but he received these answers: he should not live more than the full life of a man, but for three hundred years there should be in his line no woman and no man who was not of great repute. He was a great warrior, and went on forays far and wide in the Eastern Regions: there he slew in single combat the king who was called Sigtrygg. Then he took in marriage that woman named Alvig the Wise, daughter of King Eymund of Hólmgard [Hólmgarðr]: they had eighteen sons, nine born at one birth. These were their names:the first, Thengil [Thengill], who was called Thengil of Men; the second, Ræsir; the third, Gram [Gramr]; the fourth, Gylfi; the fifth, Hilmir; the sixth, Jöfur [Jǫfurr]; the seventh, Tyggi; the eighth, Skyli or Skúli; the ninth, Harri or Herra. These nine brothers became so famous in foraying that, in all records since, their names are used as titles of rank, even as the name of King or that of Jarl. They had no children, and all fell in battle.
Snorri then gives examples from skaldic verse where these names are used as general terms for 'lord' or 'ruler'. The promise of three hundred years of no women among Halfdan's descendants is paralleled in the story of Ríg-Jarl who has sons only but no daughters. See Ríg (Norse god). None of the titles given here duplicate titles such as hersir, jarl, konungr, and dróttinn which appear in the Ríg account. Snorri continues: Halfdan and his wife had nine other sons also; these were:Hildir, from whom the Hildings are come; Nefir, from whom the Niflungs sprang; Audi [Auði], from whom the Ödlings [Ǫðlingar] are come; Yngvi, from whom the Ynglings are descended; Dag [Dagr], from whom come the Döglings [Dǫglingar]; Bragi, from whom the Bragnings are sprung (that is the race of Halfdan the Generous (Hálfdanr inn mildi); Budli [Buðli], from whom the Budlungs [Buðlungar] are come (from the house of the Budlungs Atli and Brynhild [Brynhildr] descended); the eighth was Lofdi [Lofði], who was a great war-king (that host who were called Lofdar [Lofðar] followed him; his kindred are called Lofdungs [Lofðungar], whence sprang Eylimi, Sigurd Fáfnir's-bane's mother's sire); the ninth, Sigar [Sigarr], whence come the Siklings: that is the house of Siggeir [Siggeirr], who was son-in-law of Völsung [Vǫlsungr],—and the house of Sigar, who hanged Hagbard [Hagbarðr]. From the race of Hildings sprang Harald Red-beard [Haraldr granrauði], mother's father of Halfdan the Black [Hálfdanr inn svarti]. Of the Niflung's house was Gjúki. Of the house of Ödlings, Kjár [Kjárr]. Of the house of the Ylfings was Eirík the Eloquent [Eiríkr inn málspaki].
The Skjöldungs and Skilfings mentioned in the Hyndluljód are missing here. The Ylfings are suddenly introduced at the end in a reference to Eirík the Eloquent yet are also not found among the nine families.
Snorri then immediately mentions what seem to be intended as four famous houses not descended from Halfdan the Old: These also are illustrious royal houses:from Yngvi, the Ynglings are descended; from Skjöld in Denmark, the Skjöldungs are come; from Völsung in the land of Franks, those who are called Völsungs. One war-king was named Skelfir; and his house is called the House of Skilfings: his kindred is in the Eastern Region.