The Diocese of Egypt (, ) was a diocese of the later Roman Empire (from 395 the Eastern Roman Empire), incorporating the provinces of Egypt and Cyrenaica. Its capital was at Alexandria, and its governor had the unique title of praefectus augustalis ("Augustal Prefect", of the rank vir spectabilis; previously the governor of the imperial 'crown domain' province Egypt) instead of the ordinary vicarius. The diocese was initially part of the Diocese of the East, but in ca. 380, it became a separate entity, which lasted until its territories were finally overrun by the Muslim conquest of Egypt in the 640s.