Richard Bartlett Gregg (1885-1974) was an American social philosopher said to be "the first American to develop a substantial theory of nonviolent resistance" and an influence on the thinking of Martin Luther King, Jr
and civil-rights theorist [[Bayard Rustin]],
as well as [[Aldous Huxley]].
Gregg's ideas also influenced the [[Peace Pledge Union]] in 1930s Britain.
Gregg traveled to India in the 1920s to learn about the culture and to seek out Gandhi. His publications include Gandhiji's Satyagraha or non-violent resistance, published in 1930, and The Power of Non-Violence, from 1934. His revision, The Power of Non-Violence (1960) included a foreword by King.The book was republished in several other editions, including a Swedish translation in 1936 (as Den nya maktfaktorn: motstånd utan våld). In the 1940s Gregg became interested in ecology and organic farming, and spent severalyears living on a farm owned by Scott and Helen Nearing.
Gregg was also author of other books, including ''The Compass of Civilization'', and the essay ''The Value of Voluntary Simplicity'' (Wallingford, PA: Pendle Hill, 1936), a philosophical essay on the need and benefits of living more simply. He coined the term "[[voluntary simplicity]]".