Jan Hus; often referred to in English as John Hus or John Huss; was a Czech priest; philosopher; early Christian reformer and Master at Charles University in Prague. After John Wycliffe; the theorist of ecclesiastical Reformation; Hus is considered the first Church reformer; as he lived before Luther; Calvin; and Zwingli.

Hus was a key predecessor to Protestantism; and his teachings had a strong influence on the states of Western Europe; most immediately in the approval of a reformist Bohemian religious denomination; and; more than a century later; on Martin Luther himself. He was burned at the stake in 1415 for 'heresy against the doctrines of the Catholic Church'.