In Pwyll Pendefig Dyfed, the first branch of the Mabinogi, Hefeydd Hen (or Heyfedd the Old[1]) was the father of Rhiannon.[2]
According to legend, Hefeydd Hen tried to force his daughter Rhiannon to be married against her will to Gwawl son of Clud. She met Pwyll of Dyfed at the Mound of Arberth and planned to marry at her father's court in one year and one day. Their marriage was thwarted by Gwawl and his men. The feast was given to Pwyll and his men, but Rhiannon was given to Gwawl to marry in a year and a day. Pwyll then went to Hefeydd's court dressed as a beggar, asking for food. By a trick, Gwawl was captured and he and his men were defeated; forcing Hefeydd to allow Rhiannon to marry Pwyll in his court. Heyfedd Hir (Hir meaning "long" in Welsh, but also referring to distance in time[3]), is mentioned as one of the Seven Knights left to take charge of the Island of Britain when Bran went to rescue his sister in the second branch of the Mabinogi. He is also to be found in the 6th century epic poem Y Gododdin where the word "Hir" is used to describe no less than seven individuals.[4]