Reynold Alleyne Nicholson, (1868-1945) English orientalist who exercised a lasting influence on Islāmic studies.

Educated at Aberdeen University and the University of Cambridge, Nicholson was lecturer in Persian (1902–26) and Sir Thomas Adams professor of Arabic (1926–33) at Cambridge. He was a leading scholar in Islāmic literature and mysticism. 

The Mystics of Islam, first published in 1914, has long been recognized as a classic and definitive introduction to the message of Sufism. In this short but comprehensive work, R.A. Nicholson—who was one of the greatest Islamic scholars of the early 20th century—provides the general reader with an easy approach to the study of Islamic mysticism. He gives a broad outline of Sufism and describes the key principles, methods and characteristic features of the inner life as it has been lived by Muslims of every class and condition from the 8th century onwards. Many quotations are given, mainly in the author`s own fine translations from the original Arabic and Persian.