Dyggvi
In Norse mythology, Dyggvi or Dyggve (Old Norse "Useful, Effective") was a Swedish king of the House of Ynglings. Dyggvi died and became the concubine of Hel, Loki's daughter. Dyggvi was succeeded by his son Dag the Wise. According to Snorri Sturluson, Dyggvi was the nephew of Dan, the eponymous ancestor of Denmark, through his sister Drott, and was the first to be called King by his family. Attestations. Snorri Sturluson wrote of Dygvvi's father Domar in his "Ynglinga saga" (1225): About Dyggvi's mother Snorri had more to say: In his "Ynglinga saga", Snorri Sturluson included  a piece from "Ynglingatal" composed in the 9th century: The "Historia Norwegiæ" presents a Latin summary of "Ynglingatal", older than Snorri's quotation: The even earlier source "Íslendingabók" also cites the line of descent in "Ynglingatal" and it also gives Dyggvi as the successor of Dómarr and the predecessor of Dagr: "ix Dómarr. x Dyggvi. xi Dagr".