According to legend, Golyat had once been a knight who violated his vows, for which he was punished by the Lady of the Lake. Transformed into a giant, he fled into the mountains and would only descend into the inhabited lowlands when hunger forced him to it. There's no knowing how much truth lies in that legend, yet it is incontrovertible fact that this dangerous giant gobbled up shepherds and sheep alike, and was so widely feared, governesses used him to scare children into eating their vegetables.
Though he came across as a wild, unthinking beast, Golyat used simple tools and any item could turn into a deadly weapon in his powerful hands. When fighting Geralt, Golyat wielded a millstone, making his every blow truly crushing. Luckily, Geralt already had some experience slaying giants and made quick work of Golyat as well, with the much appreciated help of three knights - Milton de Peyrac Peyran, Palmerin de Launfal and Guillaume de Launfal.
There were many brave and true knights in the service of the old duke, but the greatest of them all was Luis Alberni. His crest showed a red field with a golden star, each of whose five points stood for one of the chivalric virtues.
Yet fame and glory went to Alberni's head. Years passed and he began to think himself the most perfect of all knights. In the end, he came to think he was virtue incarnate and there was no one in the world who preceded him in this regard, something even the Lady of the Lake must recognize. Alberni thus set off to see her and have her pay him homage in honor of his excellency.
Yet as Alberni approached the Lady's home, his body and equipment began to change. The slender knight grew more and more corpulent, until his horse could finally no longer bear him. His sword first became wooden, then turned into a mace, and his shining armor became dull and turned to ash. All he had left was his helmet, which turned into a wooden cage.
Alberni stood on the shore of the lake, wishing to speak, yet all that came from his lips was a wild cry. The knight peered at his reflection in the lake's waters and understood he had become a giant. The Lady of the Lake then emerged and said: You abandoned the chivalric virtues long ago. Of all your sins, the greatest was pride. It has changed your sword into a mace, deprived you of armor and made your flesh into that of a beast. From now on you shall be known as Golyat. Go to Mount Gorgon, where you shall live in this form far from the eyes of men, accompanied by the painful memory of your lost glory, until the day death mercifully frees you from your torment.
Launch a crosbow bolt into its eye, and ... you won.
Name of this giant is reference to biblical legend of David and Goliath and there is even an achievement David and Golyat that is earned by shooting the giant in the eye with Geralt's crossbow. Pulling off the feat instantly kills Golyat regardless of how much HP he has prior to the shot, lucky players might be able to pull it off without aiming at the giant's eye manually.
This fight may be an homage to the Spanish novel, Don Quixote, as in the book the titular character fights against windmills, thinking that they are giants.