John Fisher (c. October 19, 1469 – June 22, 1535), venerated by Roman Catholics as Saint John Fisher, is an English Catholic bishop and theologian.

He is a man of learning, associated with the intellectuals and political leaders of his day, and eventually becomes Chancellor of the University of Cambridge.

Fisher is executed by order of Henry VIII during the English Reformation for refusing to accept the king as Supreme Head of the Church of England and for upholding the Catholic Church's doctrine of papal primacy.

He is named a cardinal shortly before his death.

He is honored as a martyr and saint by the Catholic Church.

He shares his feast day with St Thomas More on June 22 in the Roman Catholic calendar of saints and on July 6 in that of the Church of England.