Ysbaddaden Pencawr, whose epithet means 'Chief Giant,' is one of the most formidable antagonists in Welsh mythology. He appears in 'Culhwch ac Olwen,' the earliest Arthurian prose tale in Welsh literature and one of the stories of the Mabinogion. From his towering, inaccessible fortress, Ysbaddaden rules over a vast domain with absolute authority, his enormous eyelids so heavy that servants must prop them open with iron forks.
The story
The heart of the tale is a prophecy: Ysbaddaden is fated to die on the day his daughter Olwen marries. When the young hero Culhwch arrives to court her — driven by a stepmother's curse that he will marry no woman but Olwen — the giant responds by setting forty seemingly impossible tasks. These range from recovering the magical comb and shears from between the ears of the enchanted boar Twrch Trwyth to obtaining the blood of the Black Witch from the head of the Valley of Grief. Each task is designed to be fatal.
With the help of his cousin King Arthur and a company of extraordinary companions, Culhwch completes every challenge. The tale culminates in Ysbaddaden's death at the hands of his own nephew, Goreu fab Custennin, who had nursed a lifelong grievance against the giant. The story is one of the richest in medieval Welsh literature, blending Arthurian romance with older Celtic giant-slaying traditions and a mythological catalogue of Britain's wonders.