Zachary Ainsworth is the father of Angelica Ainsworth and Julian Ainsworth and the previous head of the Ainsworth family in Fate/kaleid liner PRISMA☆ILLYA.
He died during the Fourth Ainsworth Holy Grail War, subsequently having his personality placed into a Doll body. He was then used by Julian as the Card User given possession of the Saber Card Class in the Fifth Ainsworth Holy Grail War.