Who was the king of the Grail castle and father of Elaine of Corbenic?

The king of the Grail castle and father of Elaine of Corbenic was King Pelles.

Pelles rules Corbenic, the enchanted castle associated with the Holy Grail in the Vulgate Cycle and later Arthurian adaptations. He belongs to the Grail-keeper lineage traced in the romances to Joseph of Arimathea and the early guardians of the sacred vessel. Elaine of Corbenic is presented as his daughter in the tradition popularized by Thomas Malory.

Pelles knows that Elaine and Lancelot will have a son destined for the Grail Quest. Through magic and deception, Lancelot is brought to Elaine, and their son Galahad is conceived. Galahad later becomes the ideal Grail knight, while Pelles remains connected with the wounded or maimed king who awaits restoration.

The name is easy to confuse with King Pellam, another figure in the Grail family, and with the title Fisher King. Medieval texts do not always keep these identities consistent. In some accounts, Pelles is himself called the Maimed King; in others, Pellam or an unnamed wounded ruler fills that role. Nevertheless, Pelles is the standard answer for Elaine’s father and the ruler of Corbenic in the best-known prose-romance tradition.