St. Catherine of Alexandria
According to Catholic Online, "Saint Catherine of Alexandria is a canonized saint in the Catholic Church who, per Christian tradition, was martyred around 305 in Alexandria, Egypt. Of course, the Church of the first Millennium was undivided. She is also recognized as the Great Martyr and Saint by the Orthodox Church. There are no surviving primary sources attesting to her existence, but the fact that her memory, and the stories about her, have been kept alive - and handed down in the tradition - certainly confirm her existence, and her life of heroic virtue and holiness."