Leonhardt is a surname. Notable people with the surname include:
Robert Leonhardt (1877–1923), Austria born baritone
Fritz Leonhardt (1909–1999), German civil engineer
Gustav Leonhardt (1928–2012), Dutch musician
Wolfgang Leonhard (1921–2014), German political author, publicist, and historian
David Leonhardt (1973–), a business journalist, and Pulitzer Prize winner with the New York Times
Paul Saladin Leonhardt
Joachim Leonhardt (1929-), German scientist and marksheider