Henry Shakespear Stephens Salt (/sɔːlt, sɒlt/; 20 September 1851 – 19 April 1939) was a British 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.

[citation needed] His circle of friends included many notable figures from late-19th and early-20th century literary and political life, including writers Algernon Charles Swinburne, John Galsworthy, James Leigh Joynes (brother-in-law), Edward Carpenter, Thomas Hardy, Rudyard Kipling, Havelock Ellis, Count Leo Tolstoy, William Morris, Arnold Hills, Ralph Hodgson, Peter Kropotkin, Ouida, J. Howard Moore, Ernest Bell, George Bernard Shaw and Robert Cunninghame-Graham, as well as Labour leader James Keir Hardie and Fabian Society co-founders Hubert Bland and Annie Besant.

[7][8] Salt's shift toward vegetarianism developed alongside his evolving social, political, and religious views, significantly influenced by Shelley, whom he regarded as a key mentor.

Salt argued that vegetarianism was not merely a dietary choice but a critical component of a broader social reform movement aimed at creating a more humane, just, and civil society, which he termed "humanitarianism".

The League's philosophy was rooted in the belief that scientific advances and evolutionary biology had debunked long-held notions of differences between races, classes, and species, advocating for universal sympathy.

The League, aligned with early organised humanism, included prominent figures like Howard Williams, Alice Drakoules, Edward Maitland, and Kenneth Romanes.

From 1897 to 1919, headquartered at Chancery Lane, the League actively campaigned against corporal punishment, blood sports, and other societal injustices through press engagements and public debates.

If we are ever going to do justice to the lower races, we must get rid of the antiquated notion of a 'great gulf' fixed between them and mankind, and must recognize the common bond of humanity that unites all living beings in one universal brotherhood.Salt's first wife died in 1919; following this, he closed down the Humanitarian League.