John R. Casani (born September 17, 1932) is an American engineer. He worked for the National Aeronautics and Space Administration (NASA) at the Jet Propulsion Laboratory, where he managed the Voyager, Galileo, Cassini and Prometheus projects. Casani was elected a member of the National Academy of Engineering in 1989 for pioneering systems engineering of planetary spacecraft and for leadership of spacecraft engineering and science teams.