Peter m. Greek πέτρος 'rock'.
The name of one of the twelve apostles, who became the first Bishop of Rome and first Roman Catholic Pope, as well as numerous saints from the 1st C onwards, five popes of Alexandria, a 10th C tsar of Bulgaria, an 11th C king of Aragon and Navarre, an 11th C tsar of Bulgaria, two 12th C emperors of Bulgaria, four 13th C kings of Aragon, two 13th C emperors of Constantinople, a 14th C king of Portugal, a 14th C king of Castile, a 14th C king of Moldavia, a 14th C king of Aragon, and a 15th C prince of Moldavia. Vulgate: Petrus. Wycliffite Bible (1395): Petre.
Diminutives in -co and -ko are indicative of Slavic influence.
The English diminutives Pere and Perkyn and the vernacular forms Peris and Perys are witnessed in 1379 in the relational bynames Peresoñ (WRYPT1 p. 22), Perissoñ (WRYPT1 p. 143), Perkynsoñ (WRYPT1 p. 15), and Peryssoñ (WRYPT1 p. 38).