Lewis Gompertz (c. 1784 – 2 December 1861) was an English writer and inventor, and early animal rights and veganism advocate. He was a founding member, in June 1824, of the English Society for the Prevention of Cruelty to Animals; later the RSPCA. Gompertz was the younger brother of the mathematician and actuary Benjamin Gompertz and the poet Isaac Gompertz.