Petru I was Voivode (prince) of Moldavia from the end of 1367 to after July 1368. He is now generally accepted to have been the son of prince Ştefan, oldest son of voivode Bogdan I of Moldavia. However, previously, he has previously been considered to be the son of Costea of Moldavia with a daughter of Bogdan I according to the historian Juliusz Demel.