Saint Cuthbert Mayne (1543 - 1577) is a saint in the Roman Catholic Church and one of the Forty Martyrs of England and Wales. He was the first seminary priest ever executed in England.

He was born in Devon and attended St. John's College at Oxford University, where he was taught by Edmund Campion and became a Roman Catholic. He entered the English college at Douai and was ordained a priest at the age of 18. In 1576, he was sent as a missionary to England. He posed as a steward to a landowner and worked to spread his faith and provide clerical services (such as eucharist, which was illegal) in Devon. Elizabeth I's agents quickly became aware of his presence, and the authorities began a systematic search for him in 1577. He was found in a hidden chamber and arrested.

He was tried in Launceston. The authorities sought a death sentence but had no legal standing for such. While there would later be an Act of Parliament making it a capital offense to receive ordination abroad, there was no such law extant. Therefore, Mayne was accused of saying mass , having a papal bull for the jubilee, wearing an Agnus Dei, and denying the spiritual supremacy of the Queen. The latter was the most significant charge, as, since Henry VIII, the monarch was the head of the established church, and therefore to answer to any other spiritual power was, in essence, to speak treason. Mayne was found guilty and sentenced to death. He was executed at Launceston on November 29, 1577.

He was beatified in 1888 and canonized along with the other Martyrs of England and Wales on October 25, 1970. His feast day in the Roman Catholic Church is November 29.