Milton Spinoza Plesset (7 February 1908 – 19 February 1991) was an American applied physicist who worked in the field of fluid mechanics and nuclear energy. He was elected to the National Academy of Engineering in 1979 for his fundamental contributions to multiphase flows, bubble dynamics, and safety of nuclear reactors. Plesset served as Professor of Engineering Science at California Institute of Technology during 1951 to 1978.