John Ralph Ragazzini (January 3, 1912 – November 22, 1988) was an American electrical engineer and a professor of Electrical Engineering. Ragazzini was born in New York City and received the degrees of B.S. and E.E. at the City College of New York in 1932 and 1933 and earned the degrees of A.M. and Ph.D. in Electrical Engineering at Columbia University in 1939 and 1941.
Ragazzini was dean of the School of Engineering and Science at New York University and during World War II he was chairman of the Department of Electrical Engineering at Columbia University, where he was involved in the Manhattan Project.
Ragazzini's notable students are Rudolf E. Kálmán (see Kalman filters), Eliahu Ibraham Jury (see Z-transform), Gene F. Franklin (see digital control), and Lotfi Asker Zadeh (see Fuzzy sets and Fuzzy logic).
Ragazzini is also credited, along with Lotfi Zadeh, in 1952, to have pioneered the development of the z-transform method in discrete-time signal processing and analysis.
In 1970 he received the Rufus Oldenburger Medal. In 1979, American Automatic Control Council named John R. Ragazzini Award after Ragazzini and he was the first recipient of the award. Ragazzini died on 22 November 1988, aged 76.