Ywain the Bastard, also called Ywain the Adventurous, is a son of King Urien

Urien

Urien , often referred to as Urien Rheged, was a late 6th century king of Rheged, an early British kingdom of the Hen Ogledd . His power and his victories, including the battles of Gwen Ystrad and Alt Clut Ford, are celebrated in the praise poems to him by Taliesin, preserved in the Book of Taliesin...

 of Gore and is a Knight of the Round Table

Round Table (Camelot)

The Round Table is King Arthur's famed table in the Arthurian legend, around which he and his Knights congregate. As its name suggests, it has no head, implying that everyone who sits there has equal status. The table was first described in 1155 by Wace, who relied on previous depictions of...

 in later Arthurian legend. He is often confused with his half brother Sir Ywain

Owain mab Urien

Owain mab Urien was the son of Urien, king of Rheged c. 590, and fought with his father against the Angles of Bernicia. The historical figure of Owain became incorporated into the Arthurian cycle of legends where he is also known as Ywain, Yvain, Ewain or Uwain...

, after whom he was named. While the older Ywain is the child of Urien and his wife Morgan le Fay

Morgan le Fay

Morgan le Fay , alternatively known as Morgane, Morgaine, Morgana and other variants, is a powerful sorceress in the Arthurian legend. Early works featuring Morgan do not elaborate her character beyond her role as a fay or magician...

, King Urien sired Ywain the Bastard on the wife of his seneschal

Seneschal

A seneschal was an officer in the houses of important nobles in the Middle Ages. In the French administrative system of the Middle Ages, the sénéchal was also a royal officer in charge of justice and control of the administration in southern provinces, equivalent to the northern French bailli...

. He is encountered frequently in Arthurian

King Arthur

King Arthur is a legendary British leader of the late 5th and early 6th centuries, who, according to Medieval histories and romances, led the defence of Britain against Saxon invaders in the early 6th century. The details of Arthur's story are mainly composed of folklore and literary invention, and...

 romance as a hearty and sensible warrior. His death comes at the hands of his cousin Gawain

Gawain

Gawain is King Arthur's nephew and a Knight of the Round Table who appears very early in the Arthurian legend's development. He is one of a select number of Round Table members to be referred to as the greatest knight, most notably in Sir Gawain and the Green Knight...

, ironically during the Quest for the Holy Grail

Holy Grail

The Holy Grail is a sacred object figuring in literature and certain Christian traditions, most often identified with the dish, plate, or cup used by Jesus at the Last Supper and said to possess miraculous powers...

. The two meet, disguised by their armor, and decide to joust. Ywain is mortally wounded and it is not until Gawain takes him to a hermitage for his last rites that he realizes he has killed his own cousin.