Thirteenth-century Welsh Arthurian prose romance, also known as Lady of the Fountain [W Chwedyl Iarlles y Ffynnawn], one of Y Tair Rhamant [Three Romances], along with Geraint ac Enid and Peredur. Manuscripts are found in the White Book of Rhydderch (c.1325), the Red Book of Hergest (c.1382–1410), and elsewhere. Lady Charlotte Guest included the romance in her translation of the Mabinogion (1846), as have later translators, but it is not a part of the four branches of the Mabinogi.
One evening when Arthur is in court at Caer Llion, the knights begin to tell stories to amuse themselves. Cynon son of Clydno speaks first, in a tale of a powerful Knight of the Fountain who overthrows all the confronts. Upon being challenged by Cei, Owain goes in search of the Knight and slays him. Then with the help of a maiden named Luned, who provides a magical ring and a stone of invisibility, he escapes the anger of the townspeople seeking to avenge the death of their lord. He subsequently marries the lord's widow, the beautiful Lady of the Fountain, Luned's mother, and rules the land for three years. Meanwhile, King Arthur and his knights have come in search of Owain. Upon arriving at the Fountain, King Arthur's men all challenge the new Knight of the Fountain (Owain) and are overthrown by him. Realizing their comrade's new identity, the knights are reunited with Owain, and the latter returns to Arthur's court after promising his wife, the Lady of the Fountain, that he will return after another three years. Owain is reminded of this promise when the Lady comes to King Arthur's court, removes the ring she has given him as a token to remember her, and charges him with betrayal. Overwhelmed with shame and remorse, Owain goes to live in the wild among beasts, allowing his hair to grow and his clothes to rot (see wild man of the wood motif). An unnamed widow finds Owain and restores him to health. Owain then departs for his kingdom, but along the way meets a white lion who shares a slaughtered roebuck with him. The white lion is revealed to be Luned, kept in durance because of her love of Owain and his desertion. With the aid of Luned as lion, Owain does battle with several foes, including Du Traws [the black oppressor] and Luned's tormentors. Owain is then restored to his kingdom, after which he is addressed as the Knight of the Fountain [W Iarll y Cawg].
Owain the Welsh Arthurian figure is generally thought to be based upon the 6th-century Owain ap Urien, who defended the kingdom of Rheged against the encroachment of the Angles. He also appears in Breuddwyd Rhonabwy [The Dream of Rhonabwy], where he plays the board-game gwyddbwyll with Arthur and is much associated with ravens. Owain ap Urien was a patron of Taliesin and subject of a lament attributed to that poet. In the Triads, Owain is described as the son of Urien and the semi-divine Modron.