Parmenian (Latin: Parmenianus; died ca. 392) was a North African Donatist bishop, the successor of Donatus in the Donatist bishopric of Carthage. He wrote several works defending the rigorist views of the Donatists and is recognized as "the most famous Donatist writer of his day", but none of his writings have survived.
Optatus of Milevis, the anti-Donatist polemicist and contemporary of Parmenian, calls him peregrinus, meaning that he was probably not a native of Africa. He may have come from Spain or Gaul.
Whatever his origin, Parmenian succeeded Donatus as Donatist bishop of Carthage around the year 350. He was banished from the city in 358. He returned in 362 under the decree of Julian that allowed exiled bishops to return to their sees. About this time, if not earlier, he published a work in five parts defending Donatism (Adversus ecclesiam traditorum), to which the treatise of Optatus is a reply. In about 372, he wrote a book against Ticonius. At an unknown year during his episcopacy, he oversaw a council of Donatist bishops that made an important proclamation about the rebaptism of traditores.
Parmenian died and was succeeded by Primian in about the year 392.
Parmenian's most influential work was written in about 362 and entitled Adversus ecclesiam traditorum ("Against the church of the traditores"). While it has been lost, it appears to have been widely read by his contemporary Catholic opponents. Optatus published his great work De schismate Donatistarum ("On the schism of the Donatists") in response to Parmenian. Judging by Optatus' response, we can infer that Parmenian held the standard rigorist position of the Donatists that "the sacrifice of a sinner is polluted," and that baptism cannot be validly conferred by a sinner, such as one of the traditores. Even while arguing against his views, however, Optatus does not refer to Parmenian as a heretic, but rather as a "brother." (It was Optatus' opinion that only pagans and heretics go to hell; he believed that schismatics and all Catholics will eventually be saved after a necessary purgatory.)