Richard Leos Jenkins (3 June 1903 – 30 December 1991) was an American psychiatrist known for his work in child psychiatry and juvenile delinquency. Jenkins earned his A.B. from Stanford University in 1925 and his M.D. from University of Chicago. In the 1930s he published on intelligence and "mongolism." His work on psychometrics with Louis Leon Thurstone found that the youngest child is usually the smartest, and children of older parents are usually smarter than peers.