Lionel Sharples Penrose (1898-1972) was a British geneticist, psychiatrist, mathematician and chess theorist, who carried out pioneering work on inherited mental illnesses.

In British psychiatry, the so-called 'Penrose's Law' states that the population size of prisons and psychiatric hospitals are inversely related, although this is generally viewed as an oversimplification. He was also a lead figure in the Medical Association for the Prevention of War in the 1950s.

Penrose is the father of mathematician Oliver Penrose , scientist Roger Penrose (with whom he co-authored papers on the Penrose triangle) and chess grandmaster Jonathan Penrose.