Olaus Petri, originally Olof Persson, (January 6, 1493 - April 19, 1552) was a Swedish clergyman and protestant reformer. He was the brother of Laurentius Petri the first Evangelical Lutheran Archbishop of Sweden.
Petri studied at the University of Wittenberg, where he was influenced by Philipp Melanchthon and the works of Martin Luther. The reformation in Sweden was lead by King Gustav Vasa and under him Petri was the principal reformer.
Mikael Agricola, his counterpart in Finland, was both the principal reformer and Bishop of Åbo.
