John Frith, English priest, writer, and martyr (b. 1503)
John Frith (1503 – 4 July 1533) was an English Protestant priest, writer, and martyr.

Frith was an important contributor to the Christian debate on persecution and toleration in favour of the principle of religious toleration. He was 'perhaps the first to echo in England' of that 'more liberal tradition' of Zwingli, Melanchthon and Bucer. As his ministry progressed, Frith took greater risks with his stance against the Roman Catholic teachings of Purgatory and Transubstantiation. He was eventually brought before Thomas Cranmer and the Inquisition for his teachings and condemned to be burned at the stake for heresy.

In his revision of Foxe's Book of Martyrs, author Harold Chadwick writes the following about John Frith: "Master Frith was a young man noted for his godliness, intelligence, and knowledge. In the secular world, he could have risen to any height he wished, but he chose, instead, to serve the Church and work for the benefit of others and not himself." During his studies, he became acquainted with William Tyndale who deeply influenced Frith's beliefs. Like Tyndale and Luther, Frith played an influential role in the Protestant Reformation.