American Theosophical author who served in various capacities at Adyar and in the Australian Section. Neff was born on September 7, 1877, in Akron, Ohio. During 1911-13 she was resident at Adyar, where she worked in the Theosophical Publishing House and the Adyar Library, and for a time was private secretary to Charles W. Leadbeater. She was also in charge of the business department of the Boys' High School at Madanapalle and Vasanta Ashrama, a Theosophical boarding school for Indian girls.

Neff served for five years as principal of the Middle School for Girls at Lucknow, where she introduced many reforms and was Organizing Secretary for the Anti-tuberculosis League. During 1922-23, Neff assisted J. J. van der Leeuw at King Arthur's School, North Sydney, Australia. She served for two years as Assistant General Secretary and National Lecturer for the Australian Section of the Theosophical Society. In 1925 she returned to Adyar at the request of C. Jinarajadasa to take charge of the archives, again acting as secretary to Leadbeater. 

Neff's publications include The "Brothers" of Madame Blavatsky (1932), Personal Memoirs of H. P. Blavatsky (1937,1967), The Mahatma Letters: Their Chronological Order (1940), Letters of H. P. Blavatsky to A. P. Sinnett: Their Chronological Order (1940), A Guide to Adyar (1943), and How Theosophy Came to Australia and New Zealand (1943).