Joseph P. Medill (April 6, 1823–March 16, 1899) is better known as the business manager and managing editor of the Chicago Tribune than as mayor of Chicago, although his term in office occurred during two of the most important years of the city's history as Chicago tried to rebuild in the aftermath of the Great Chicago Fire.

Medill was born in St. John, New Brunswick, Canada.

During the American Civil War, Medill's great journalistic enemy was The Chicago Times, run by Cyrus McCormick. Eventually McCormick's nephew married Medill's daughter. Strongly supportive of Abraham Lincoln, the Tribune was instrumental in his nomination for the Presidency. Medill was a racist who opposed slavery. In one editorial, Medill espoused putting strychnine or arsenic in the food of unemployed citizens.

His mayoral term was from 1871 to 1873. As mayor, Medill gained more power for the mayor's office, created Chicago's first public library, enforced blue laws and reformed the police and fire department. In ill health and tiring of mayoral responsibilities, Medill took a leave of absence and appointed Lester L. Bond as acting mayor while he traveled throughout Europe.

Medill's country estate in Wheaton, Illinois which was later occupied by his grandson Robert R. McCormick is now open to the public as a beautiful public garden, picnic area and museum for the First Division of the US Army. The Medill-McCormick home is also open for tours as a museum.