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'.