Sir Galahad , in Arthurian legend, is a knight of King Arthur's Round Table and one of the three achievers of the Holy Grail. He is the illegitimate son of Lancelot and Elaine of Corbenic, and is renowned for his gallantry and purity. Emerging quite late in the medieval Arthurian tradition, Sir Galahad first appears in the LancelotâGrail cycle, and his story is taken up in later works such as the Post-Vulgate Cycle and Sir Thomas Malory's Le Morte d'Arthur.