James Block Zagel (born March 4, 1941) is a United States district judge for the United States District Court for the Northern District of Illinois and a novelist.
Born in Chicago, Zagel is the son of Samuel S. Zagel (1905–1999), a native of Warsaw, Poland who had immigrated to Chicago in 1915, and Ethel Samuels Zagel (1911–1986). Zagel earned a bachelor's degree from the University of Chicago in 1962 and a master's degree from the University of Chicago in the same year. He then earned a law degree from Harvard Law School in 1965.
Zagel began his career as an assistant state's attorney in Cook County, Illinois from 1965 until 1969. He then served as an assistant attorney general for the State of Illinois from 1969 until 1977. Concurrent to the job as assistant attorney general, Zagel ran the Criminal Justice Division in the attorney general's office from 1970 until 1977, and he also served as chief prosecuting attorney for the Illinois Judicial Inquiry Board from 1973 until 1975.