Galahad was a later addition to the Round Table, especially famed for his escapades in the search for the Holy Grail. Galahad is the son of Lancelot, but he only saw Lancelot as a father while he was a boy and both never got along that well. Galahad was admired as the perfect knight, the young boy who would shoulder the next generation of the Round Table. He was a "saint who was the only one to obtain the Holy Grail, just to return it to heavens."
Lancelot comments that Mash Kyrielight is wearing her hair in a similar style to him.
In the year 2010, Galahad was the second Heroic Spirit summon by Chaldea Security Organization. However the summoning was an experiment aimed to control the powers of Galahad by binding him to Mash Kyrielight in order to produce a Demi-Servant. While the project succeeded in summoning and binding a spirit to Mash, the spirit failed to awaken. Whilst summoned within Mash Kyrielight, he was disgusted by Marisbury Animusphere and Chaldea's various inhumane experiments. Taking over Mash's body, Galahad broke free of the restraints holding him in place and destroyed Chaldea's countermeasures, including multiple barriers keeping the staff safe. He was stopped from killing Marisbury when Mash began resisting. Realizing Mash will immediately die if he leaves, he instead chose to hibernate. When Lev Lainur Flauros caused the explosion in Chaldea's CHALDEAS room, Mash was amongst the causalities. As she was dying, Galahad formed the Demi-Servant contract with her. In exchange for a Heroic Spirit's ability and Noble Phantasm, he wanted to eliminate the cause of ‘Singularity Point F’. Mash obtained his fighting experience, skills, and Noble Phantasm, but lacks even knowledge of who is fused with her until later in the story. After granting her his skills and Noble Phantasm Galahad faded away.
As Mash goes through her second to last Saint Graph Ascension, Bedivere describes her appearance is completely like Galahad.
