William Farel (1489 - 13 September 1565), ne Gillaume Farel, a French evangelist, and founder of the Reformed Church in the canton of Neuchâtel, Berne, Geneva and Vaud in Switzerland. He was remembered for having persuaded John Calvin to remain in Geneva in 1536, and to persuade him to return there in 1541, after their expulsion in 1538. They influence the government of Geneva to be a theocratic state "Protestant Rome", a refuge for the Protestants. Along with Calvin, Farel worked to train missionary preachers who spread the Protestant influence on other countries, especially France.


Farel was a fiery preacher and an energetic critic of the Roman Catholic Church. In the early years of the Reformation in France, he was a disciple of the pro-reform Catholic priest, Jacques Lefevre d'Etaples.