“Llenlleawc the Irishman”
Llenlleawg Wyddel
In Culhwch, one of Arthur’s warriors, from the headlands of Gamon in Ireland. He is called “the exalted one”.
Llenlleawg accompanied Arthur to Ireland the quest to obtain the cauldron of Diwrnach. Upon Diwrnach’s refusal to hand it over, Llenlleawg grabbed Arthur’s sword Caledfwlch and killed Diwrnach.
He is to be identified with Llwch Lleminawc (Lluch Lleawg) or Lleminawg who appears in a similar role of companion to Arthur in the Preiddeu Annwfn. It is possible that both Llenlleawc and Llwch Lleminawc formed the prototype character of Sir Lancelot.
Source
Culhwch and Olwen | Late 11th century