John Wentworth, American journalist and politician, 19th Mayor of Chicago (d. 1888)
John Wentworth (nicknamed "Long John") (March 5, 1815 – October 16, 1888) was the editor of the Chicago Democrat, publisher of an extensive Wentworth family genealogy, a two-term mayor of Chicago, and a six-term member of the United States House of Representatives, both before and after his service as mayor.

After growing up in New Hampshire, he joined the migration west and moved to the developing city of Chicago in 1836, where he made his adult life. Wentworth was affiliated with the Democratic Party until 1855; then he changed to the Republican Party. After retiring from politics, he wrote a three-volume genealogy of the Wentworth family in the United States.