Peter I

Peter I may refer to:

Religious hierarchs

 * Saint Peter (c. 1 AD – c. 64–88 AD), a.k.a. Simon Peter, Simeon, or Simon, apostle of Jesus
 * Pope Peter I of Alexandria (died 311), revered as a saint
 * Peter I of Armenia (died 1058), Catholicos of the Armenian Apostolic Church
 * Peter I (bishop of León) (died after June 1112)
 * Peter I (archbishop of Lyon) (died 1139), a Benedictine monk

Rulers

 * Peter I of Bulgaria (died 970), emperor (tsar) of Bulgaria
 * Peter I of Savoy (c. 1048–1078), count of Savoy
 * Peter I of Aragon and Navarre (c. 1068–1104), King of Aragon and Pamplona
 * Peter I of Barcelona, Peter II the Catholic (1178–1213), King of Aragon, Count of Barcelona
 * Peter I of Constantinople (died 1219), emperor, Peter II of Courtenay
 * Peter I, Duke of Brittany (1187–1250), Peter Mauclerc
 * Peter I, Count of Urgell (1187–1258), second son of King Sancho I of Portugal
 * Peter I of Valencia (1239–1285), Peter the Great, Peter III of Aragon, king
 * Peter I, Duke of Bourbon (1311–1356), second Duke of Bourbon
 * Peter I of Portugal (1320–1367), king of Portugal, Peter the Just, Peter the Cruel
 * Peter I of Cyprus (1328–1369), Pierre I de Lusignan, king of Cyprus and titular King of Jerusalem
 * Peter of Castile, (1334 –1369) king of Castile and León, Peter the Just, Peter the Cruel
 * Petru I of Moldavia, prince of Moldavia 1367–1368
 * Peter I, Count of Saint-Pol (1390–1433), Peter of Luxembourg
 * Pedro I of Kongo (ruled 1543–1545), Pedro I Nkanga a Mvemba
 * Peter the Great (1672–1725), Peter I, first Russian czar titled emperor
 * Peter I of the Miskito nation, ruled 1729–1739
 * Peter I of Montenegro (1747–1830), Petar I Petrović-Njegoš, legate of Serbian Orthodox Church
 * Peter I, Grand Duke of Oldenburg (1755–1829), Peter Frederick Louis of Holstein-Gottorp
 * Pedro I of Brazil (1798–1834), founder and first ruler of the Empire of Brazil
 * Peter I of Serbia (1844–1921), the last King of Serbia