Answer:
Sir Galahad.
Explanation:
Sir Galahad, the son of Lancelot in King Arthur's Knights, is best known as the knights who achieves the holy grail. He becomes the chief Grail knight, and replaces Perceval in this role.
At the feast of Pentecost, he arrives in Camelot, where he is able to sit in the Siege Perilous, an act which demonstrates that he is the knight who will achieve the Grail.
