Sir John Mason (1503 – April 20, 1566) was an English diplomat and spy.
Mason was born in Abingdon in Berkshire (now Oxfordshire). He was educated at the school at the abbey in his native town, where his uncle was abbot. Later, he went to All Souls College, Oxford and was ordained a priest. He became Chancellor of Oxford University.
He worked for several Tudor monarchs collecting information from the Continent and as a diplomat. He was knighted by Edward VI and made Dean of Winchester.
John Mason School, a secondary school in Abingdon, is named after him.