History of Christianity
John Calvin was a French cleric and doctor of law turned Protestant reformer in the second generation of the Reformation.   He was well known for publishing the Institutes of the Christian Religion, in 1536 (later revised), and became a leader of the Reformed church in Geneva, which became an "unofficial capital" of Reformed Christianity in the second half of the sixteenth century.  He had great authority in the city and over the city council, such that he has (rather ignominiously) been called a "Protestant pope".