(Sir) William Owen Chadwick, OM, KBE, FBA, FRSE, DD, Hon DLitt., was born 20 May 1916 and is a British professor, writer and prominent theologian. Brother of The Rev. Prof. (Sir) Henry Chadwick, also an extremely distinguished historian of the early Church, and a former Dean of Christ Church, Oxford, and Master of Peterhouse, Cambridge, and of the late Sir John Chadwick, British ambassador to Australia.

Chadwick attended the Tonbridge School and St John's College, Cambridge, were he received a Blue in Rugby and a First in History; then, he attended Cuddesdon College; and following, was ordained to the Church of England. After the War, (during which he was Chaplain of Tonbridge) he was made fellow of Trinity Hall, Cambridge in 1947. He was elected Master of Selwyn College, Cambridge in 1956, retiring in 1983; two years later, he was named Dixie Professor of Ecclesiastical History, during which time he began to chair the Archbishops' Commission on Church and State (1967-1971). In 1968 he was elected Regius Professor of Modern History, a chair which he held until 1982; and was President of the British Academy during the early 1980s. He was Vice Chancellor of Cambridge during a turbulent time in the late 1960s, an office which he carried out with grace; and Chancellor of the University of East Anglia after his retirement. He was created a Knight of the British Empire in 1982 and given the extraordinary honour of the Order of Merit in 1983. He has written many books, on the formation of the papacy in the Modern world; on Lord Acton; on the secularization of European thought and culture; on the Reformation; on the Church of England in England and elsewhere. He is considered the doyen of church historians in the modern period.