R. E. O'Callaghan

Robert Elliott O'Callaghan (1855 – 21 December 1936) was an English activist and writer. He was active in the vegetarian movement from the 1880s, serving as official lecturer for the Vegetarian Association, secretary of the London Vegetarian Society, and inaugural secretary of the Vegetarian Federal Union. He was also active in anti-vivisection and humane causes, founding the Catholic Humane League in 1900 and later serving in anti-vivisection organisations in northern England, and becoming a member of the Humanitarian League.

O'Callaghan became interested in vegetarianism after encountering a report of a lecture by Francis William Newman. He was known for his public lectures on vegetarianism, often illustrated with magic lantern slides, and later became proprietor of the Wheat Sheaf vegetarian restaurant in London. He also wrote and co-authored several vegetarian publications, including The Best Diet for a Working Man and The Manual of Vegetarianism.