Reuben Swinburne Clymer (November 25, 1878 - June 3, 1966) succeeded Edward H. Brown as Supreme Grand Master of Fraternitas Rosae Crucis in 1922, and served until his death, when he was succeeded by his son Emerson Myron Clymer. He had reached the rank of Grand Master in 1905.

A co-founder of FUDOFSI, which recognized the Fraternitas as the authentic Rosicrucian organization rather than AMORC, he tried to rekindle the organization after the death of leader Constant Chevillon in World War II. After the war he regarded the FRC as the world, rather than American,headquarters of Rosicrucianism.

External link