(24 January 1909 – 12 May 2005), also known as Abū Bakr Sirāj ad-Dīn, was an English writer, Islamic scholar, and philosopher. A student of the Swiss metaphysician Frithjof Schuon and an authority on the work of William Shakespeare, he is best known as the author of Muhammad: His Life Based on the Earliest Sources, first published in 1983 and still in print.