Prentice Henry Marshall (August 7, 1926 – May 24, 2004) was a United States District judge on the United States District Court for the Northern District of Illinois.
Born in Oak Park, Illinois, Marshall graduated from Oak Park High School (now Oak Park and River Forest High School) in 1944 and then served two years in the United States Navy. Under the G.I. Bill, he studied at the University of Illinois at Urbana-Champaign, earning a bachelor's degree in 1949. While there he was a member of the Phi Kappa Psi Fraternity. Marshall then earned a law degree from the University of Illinois College of Law in 1951.
Marshall then served as a law clerk for Judge Walter C. Lindley on the United States Court of Appeals for the Seventh Circuit from 1951 until 1953.
A Democrat, Marshall worked in private legal practice in Chicago from 1953 until 1967 at Johnston, Thompson, Raymond & Mayer (which later became known as Jenner & Block), becoming partner in 1961. While at Jenner, Marshall also served as a special assistant attorney general for the state of Illinois from 1964 until 1967. Marshall also built a reputation for starting Jenner's pro bono legal program. Marshall then served as a law professor at the University of Illinois College of Law from 1967 until 1973 and as a hearing officer for the Illinois Fair Employment Practices Commission from 1967 until 1972.
In 1959, Marshall, then a resident of Wheaton, Illinois, ran unsuccessfully as a Democrat for state's attorney in DuPage County, a Republican stronghold.