Jan Hus, sometimes anglicized as John Hus or John Huss, and referred to in historical texts as Iohannes Hus or Johannes Huss, was a Czech theologian and philosopher who became a Church reformer and the inspiration of Hussitism, a key predecessor to Protestantism, and a seminal figure in the Bohemian Reformation. Hus is considered to be the first Church reformer, even though some designate the theorist John Wycliffe. His teachings had a strong influence, most immediately in the approval of a reformed Bohemian religious denomination and, over a century later, on Martin Luther.

John Wycliffe was an English scholastic philosopher, theologian, purported biblical translator, reformer, Catholic priest, and a seminary professor at the University of Oxford. He became an influential dissident within the Catholic priesthood during the 14th century and is considered an important predecessor to Protestantism. Wycliffe questioned the privileged status of the clergy, who had bolstered their powerful role in England, and advocated radical poverty of the clergy.