William Spenser, an English Roman Catholic priest, was executed at York on 24 September 1589. Robert Hardesty, a layman who had sheltered him, was executed with him.

Spenser was born in Yorkshire and studied at Trinity College, Oxford, where he became a fellow and received his MA in 1580. He became increasingly committed to Catholicism and left England in 1582. At Reims, he entered the Catholic Church and was ordained a priest in 1583.

He returned to England in 1584 as a missionary priest. Under legislation passed during the reign of Elizabeth I, Catholic priests ordained abroad faced severe penalties for entering and remaining in England. Spenser also spent time helping Catholic prisoners at York.

He was eventually arrested and prosecuted under the 1585 Act against Jesuits, seminary priests and other Catholic clergy. His status as a priest and his return to England formed the basis of the case against him.

Hardesty was condemned for sheltering and assisting Spenser while knowing that he was a priest. The two men were executed together at York.

In 1987, Pope John Paul II beatified Spenser and Hardesty as two of the Eighty-five Martyrs of England and Wales.