John Fisher was educated at Cambridge — Michaelhouse, then St. Anne's — and was ordained priest in 1491. He rose through Cambridge academic offices to become Master of Michaelhouse (1497), Vice-Chancellor (1501), and Chancellor of Cambridge University (1504 — an office he held until his death). He was the executor of the will of Lady Margaret Beaufort (Henry VII's mother), the foundress of Christ's College and St. John's College, Cambridge; St. John's College, in particular, owes its existence directly to his administrative care.
Bishop of Rochester from 1504 (the smallest and poorest English diocese, which he made his by deliberate choice), he was the most learned English theologian of his generation. He brought Erasmus to teach at Cambridge, defended Catholic doctrine against Luther in eight massive treatises (the Confutatio of 1523 and the Defensio of 1526), and was the only English bishop to oppose Henry VIII's divorce and royal supremacy from the beginning.
Imprisoned in the Tower from April 1534 for refusing to swear the Oath of Succession, he was excluded from food, clothing, and writing materials for fourteen months. Pope Paul III created him cardinal in May 1535 — Henry VIII said, 'When he gets here, the hat shall not have a head to put it on.' He was beheaded on Tower Hill on June 22, 1535, the day after the cardinal's hat reached London. Canonized with Thomas More in 1935.