Heinrich Bullinger was a Swiss Reformer and theologian, the successor of Huldrych Zwingli as head of the Church of Zürich and a pastor at the Grossmünster. One of the most important leaders of the Swiss Reformation, Bullinger co-authored the Helvetic Confessions and collaborated with John Calvin to work out a Reformed doctrine of the Lord's Supper.

Protestant Reformers were theologians whose careers, works and actions brought about the Protestant Reformation of the 16th century.