Arethas of Caesarea was a 10th-century Byzantine archbishop and theologian born in Patras. A student of Photius at the University of Constantinople, he rose to the position of Archbishop of Caesarea Mazaca in 903. He was a prominent figure in the imperial court, particularly during the marital controversies involving Emperor Leo VI. Beyond his ecclesiastical duties, he was a prolific scholar and bibliographer who played a vital role in preserving classical Greek literature and early Christian writings through his extensive manuscript production.