Alfred Guillaume (1888–1965) was an Arabist and Islamic scholar.
Guillaume took up Arabic after studying Theology and Oriental Languages at the University of Oxford. In the First World War he served in France and then in the Arab Bureau in Cairo. Guillaume was a Christian.
He became Professor of Arabic and the Head of the Department of the Near and Middle East in the School of Oriental and African Studies, in the University of London. He was later Visiting Professor of Arabic at Princeton University, New Jersey.
During the Second World War the British Council invited him to accept a visiting professorship at the American University of Beirut where he greatly enlarged his circle of Muslim friends. The Arab Academy of Damascus and the Royal Academy of Baghdad honoured him by electing him to their number, and the University of Istanbul chose him as their first foreign lecturer on Christian and Islamic theology.
He was best known as the author of Islam, published by Penguin Books, and as co-author, with Sir Thomas Arnold, of The Legacy of Islam, in the Legacy series, which has been translated into several languages. He also translated Ibn Ishaq's "Sirah Rasul Allah", published as The Life of Muhammad. A translation of Ishaq's "Sirat Rasul Allah".