Culhwch and Olwen
The tale was popularised by Lady Charlotte Guest in her translation of the Mabinogion. Culhwch and Olwen is believed to be the earliest Arthurian romance, and is one of Wales' earliest existing prose texts.
The tale has a simple plot but an often complex cast of characters. It begins with Cylidd Wledig (King Kilydd), son of Celyddon, who marries Goleuddydd. She becomes pregnant, but loses her sanity before the birth.
Their son, Culhwch, is born in a pig-run, and is raised in secret by a swineherd until he comes of age.
Goleuddydd dies soon after Culhwch's birth. When looking for another wife, Cilydd kills King Doged, taking his widow, daughter and land as his own.
Cilydd's new queen is unhappy that he doesn't have a direct heir, but calls Culhwch to court when she learns of his existence. She suggests that Culhwch should marry her daughter, guaranteeing succession.
Culhwch refuses, offending the queen. Enraged, she puts a curse on him for foiling her plans: he will marry no-one but the beautiful Olwen, daughter of Ysbaddaden Pencawr, king of giants.
Although yet to see her, Culhwch becomes infatuated with Olwen, but his father warns that he will never find her without the help of his famous cousin King Arthur. Culhwch sets off to Arthur's court in Celliwig, Cornwall - one of the first known instances of the court being given a specific location.
Arthur sends scouts to find Olwen. They search for a year but find no sign of her, so Culhwch's friend Cei (known in later literature as Sir Kay) suggests they go looking for Olwen themselves.
Arthur picks six of his finest men to join Culhwch on the search, including Cai, Bedwyr (Sir Bedivere) and Gwalchmei (Sir Gawain, Arthur's nephew).
The group reaches the house of a shepherd, whose wife - the sister of Culhwch's mother - tries to discourage Culhwch from searching for Olwen. She explains that all men who look for her are never seen again.
Unable to dissuade Culhwch, the shepherd's wife tells him that every Saturday Olwen comes to their house to wash her hair.
When Olwen arrives, white flowers spring up in her footprints wherever she walks - hence her name, meaning 'white track'. Culhwch is stunned by her beauty and falls instantly in love.
Although she is receptive to Culhwch, Olwen explains that Ysbaddaden is fated to die whenever his daughter marries, and will only give his consent if Culhwch completes a series of immensely difficult tasks.
Culhwch and his men follow Olwen back to the castle to see her father. The following day he gives Culhwch a huge list of tasks to do before he can marry Olwen, which include cutting Ysbaddaden's hair and shaving his beard.
The first task is to find Wrnach the giant, whose sword is needed to kill Twrch Trwyth, an Irish king who has been turned into a boar. When they find Wrnach, Cei persuades him that his sword needs sharpening. As the giant hands over the weapon, Cei beheads him.
Next they search for Mabon ap Modron, who is imprisoned in a watery Gloucester dungeon. Mabon is the only man able to handle Drudwyn the hound, who is needed to catch Twrch Trwyth. The men enlist the help of Arthur, whose army attacks Gloucester and frees Mabon.
They then hunt down and kill Ysgithyrwyn, the wildest boar in the land. The warriors take its tusk, the only thing sharp enough to complete their task. They then follow Twrch Trwyth to Ireland, but he escapes to Preseli in North Wales.
After a cross-country chase in which Arthur loses many men, the men trap Twrch Trwyth on the banks of the River Severn. They take the shears, comb and razor that lie between his ears, and Twrch is driven into the sea and drowned.
Finally, Arthur himself kills the Black Witch, taking her blood to soften the beard of Ysbaddaden. Culhwch heads back and cuts Ysbaddaden's hair and shaves his beard to the bone.
Ysbaddaden dies, allowing Culhwch and Olwen to get married.