Leonard Darwin FRGS (15 January 1850 – 26 March 1943) was an English politician, economist and eugenicist.

He was a son of the naturalist Charles Darwin, and also a mentor to Ronald Fisher, a statistician and evolutionary biologist.

He considered himself the least intelligent of their children – brothers Frank, George and Horace were all elected Fellows of the Royal Society.

He wrote vigorously on the economic issues of the day: bimetallism, Indian currency reform and municipal trade.

[3] Darwin played an important part in the life of the geneticist and statistician Ronald Fisher, supporting him intellectually, morally and sometimes financially.

"[5] Darwin retired to Cripps Corner at Forest Row, East Sussex in 1921, with his second wife Charlotte Mildred Massingberd (died 1940), and lived there until his death in 1943.