Perpetua Kirk is a character from Christianna Brand's mystery novel "Death of Jezebel". She is one of the six suspects in a murder taking place at a medieval-themed fair, the supposed motivation of which was a suicide she indirectly caused years before, and for which her life has now been threatened.
Perpetua Fancourt is a character in the Harry Potter series, who was mentioned in the video games. She was a witch who is credited with the invention of the lunascope, an astronomical device used to analyse the phases of the moon.