Spirito Mario Viale (born 7 February 1882) was an Italian engineer.
He was an early manufacturer of aircraft engines, producing a series of 3-, 5-, and 7-cylinder radials from a workshop in Boulogne-sur-Seine from 1910 until the outbreak of World War I.
The rise of fascism drove him back to England, where he found work as chief designer of Rolls-Royce's armaments division.
W. A. Robotham recalls him as a brilliant mathematician and talented designer; unfortunately in wartime with glasses and a pointed beard he looked like a foreign secret service agent from novels of the 1920s!
[1] When these projects were abandoned, he returned to work on aero engines with Rolls-Royce until his retirement in 1947.