Olwen is a Cymric (Welsh) goddess known from the Mabinogion of Culhwch ac Olwen where she is the titular geroine of the tale and the reason for Culhwch’s quest. Olwen is Ysbadadden the giant’s daughter and to attain Olwen’s hand Culhwch must accomplish a set of seemingly-impossible tasks.

Olwen is the eponymous heroine of the Mabinogion of Culhwch ac Olwen and the object of Culhwch’s quest. Seeking to secure a dynasty for her child, the second wife of Culhwch’s father, Cilydd fab Celyddon Wledig summons Culhwch to her and offers her daughter in marriage. However, Culhwch refuses and as a result the Lady places a tynged (fate) upon the youth that he would not wed until he obtained the hand of Olwen, daughter of Ysbaddaden chief of the Giants. Instantly, on hearing Olwen’s name Culhwch fell madly in love with her and as he made his way from the Llys his father spied him and asked him why he was so downcast. Culhwch related what had befallen and Cilydd counselled him to go to his uncle, Arthur’s court. Whereupon his long hair of youth would be cut and on entering adulthood he could ask the great Lord a boon.

Culhwch journeys to Arthur’s court and asks his boon, which is given and the warriors of Arthur’s court are sent to assist Culhwch, even though Arthur had not heard of Olwen and her kin. Thus the teulu, the members of Arthur’s court were sent out to seek-out news of Olwen. Which is how Culhwch along with Arthur’s champions, Cei, Bedwyr and Gwrhyr found themselves in the house of Custennin the brother of Ysbadadden and his wife. he, on hearing whom Culhwch is feels both joy that her nephew, the son of her sister has returned to her and sorrow that any man questing the hand of Olwen is fated to die. But she tells the travellers that Olwen comes every Saturday to wash her hair and they contrive to get a message to the fair maiden, who responds by coming to them. As Olwen walks white flowers spring up wherever she had trod and this explains her name ol-wen (literally ‘white track’). Culhwch pledges his love to Olwen when she arrives and they make their way to Ysbadadden’s court, slaying the nine watchmen and the nine watchdogs on the way. This way Culhwch comes into the presence of Ysbadadden and asks for Olwen’s hand. However, Culhwch cannot gain the hand of Olwen until a series of seemingly-impossible tasks have been achieved, including the finding of the world’s oldest prisoner, Mabon and the slaying of the great boar the Twrch Trwyth.

With the aid of Arthur all of Ysbadadden’s conditions are met and the wedding feast of Culhwch and Olwen is set. At the feast Goreu the son of Custennin avenges the murder of his brothers by killing Ysbadadden and thus the way is made clear for Culhwch to marry Olwen.

Outside the Mabinogion there is no mention of Olwen in the other mythological tales and poems, though the gogynfeirdd Dafydd ap Gwilyn and the sixteenth century poet Siôn Brwynog knew of Olwen as a paragon of beauty. As a daughter of the giant Ysbadadden could be considered one of the Plant Llŷr the Cymric race of giants and the descendants of Llŷr. Beyond this Olwen’s attributes are not entirely evident from the tale of Culhwch ac Olwen though she would appear to be an aspect of the ‘flower maiden’, the virginal bride and the guardian of the sacral kingship embodied in the form of her father the ‘Chief of the Giants’.

In terms of Olwen’s name it should also be noted that the Old Cymric word olwen was originally probably cognate with the Irish alaind ‘fair’, as pointed out by Professor Lloyd-Jones. Thus Olwen’s original meaning was ‘Fair’; however, as the original meaning was lost a false etymology rose-up to explain her name, thus the incorporation of the story about the white flowers growing from her footprints in the Mabinogi. A confusion that continues even today.