Henry Stephens Salt (20 September 1851 – 19 April 1939) was an English writer and campaigner for social reform in the fields of prisons, schools, economic institutions, and the treatment of animals. He was a noted ethical vegetarian, anti-vivisectionist, socialist, and pacifist, and was well known as a literary critic, biographer, classical scholar and naturalist. It was Salt who first introduced Mahatma Gandhi to the influential works of Henry David Thoreau.