Maddy is a surname. Notable people with the surname include:
Darren Maddy (born 1974), English cricketer Joseph E. Maddy (1891–1966), American music educator Kenneth L. Maddy (1934–2000), American politician Paul Maddy (born 1962), Welsh former footballer Penelope Maddy, Professor of Logic and Philosophy of Science and of Mathematics at the University of California, Irvine Yulisa Pat Amadu Maddy (1936-2014), Sierra Leonean actor, dancer, director and playwright