In Welsh mythology, Culhwch (pronounced "Kilhooch", the "ch" sound being the same as the Scottish "Loch") was a hero who rescued Mabon from Annwn.
Some time later, Culhwch had been arranged to marry his own stepsister, but he refused. Angry, his stepomother cursed him to marry no one but Olwen. Olwen's father, Ysbaddaden, was a vicious monster that would die if he was separated from his daughter. After many trials and tribulations, Culwch succeeded with the aid of Mabon ap Modron and gained Ysbaddaden's powers and life.
In Welsh mythology, Culhwch (pronounced "Kilhooch" with the "ch" as in the Scottish "loch") is the son of Kilydd son of Kelyddon and Goleuddydd, a cousin of Arthur and the protagonist of the story Culhwch and Olwen found in the Mabinogion.
According to the narrative, Culhwch is born to his maddened mother Goleuddydd after she is frightened by a herd of swine.
Culhwch is described as being "of gentle lineage".
Olwen is receptive to Culhwch's attraction, but she cannot marry him unless her father agrees, and he, unable to survive past his daughter's wedding, will not consent until Culhwch completes a series of about forty impossible-sounding tasks.
Fortunately for Culhwch (and the reader), the completion of only a few of these tasks is recorded and the giant is killed, leaving Olwen free to marry her lover.
The story is on one level a typical folktale, in which a young hero sets out to wed a giant's daughter, and many of the accompanying motifs reinforce this (the strange birth, the jealous stepmother, the hero falling in love with a stranger after hearing only her name, etc.).