Owein (or Owain) was the son of Urien, king of Rheged c.590 AD, and fought with his father against the Northumbrian English.

Our chief reference to Owain is in the poems of Taliesin, Urien's bard. The poem GWEITH ARGOED LLWYFAIN (the battle of Argoed Llwyfain) tells of Owain's part in a battle between the men of Rheged under Urien and the men of Northumbria under "Fflamddwyn" or Firebrand, possibly the Anglian king Theoderic. When Fflamddwyn demands hostages, Owain shouts defiance and inspires the men of Rheged to fight rather than give tribute to the English. Taliesin also composed MARWNAD OWAIN, an elegy to Owain, which suggests, as no elegy to Urien exists or has survived, that Owain predesceased his father and was never king of Rheged. In the poem it is said that Owain slew Fflamddwyn-

  Pan laddodd Owain Fflamddwyn  Nid oedd fwy nogyd cysgaid
  Cysgid Lloegr llydan nifer    A lleufer yn eu llygaid
  A rhai ni ffoynt haeach       A oeddynt hyach na rhaid
  Owain a'u cosbes yn ddrud     Mal cnud yn dylud defaid
  
  When Owain slew Fflamddwyn it was no more to him than to sleep
  The wide host of Lloegr(England)sleeps with the light in their eyes
  And those that did not flee were braver than was needed
  Owain punished them harshly like a pack of wolves chasing sheep
 
In later times Owain was drawn into the Arthurian cycle of legends, appearing in the Mabinogion tale of the Lady of the Fountain and appearing in Sir Thomas Malory's Le Morte d'Arthur as Sir Uwain.