Olof Persson, sometimes Petersson, better known under the Latin form of his name, Olaus Petri, was a clergyman, writer, judge, and major contributor to the Protestant Reformation in Sweden. His brother, Laurentius Petri, became the first Evangelical Lutheran Archbishop of Sweden.

The Reformation in Sweden is generally regarded as having begun in 1527 during the reign of King Gustav I of Sweden, but the process was slow and was not definitively decided until the Uppsala Synod of 1593, in the wake of an attempted counter-reformation during the reign of John III (1568–1592).