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- J. Ottis Adams (1851–1927) — painter Notable People
- J. Wilbur Haley Elementary School Schools & Colleges
- James A. Jenney and Charles D. Jenney: the arc-light patents Inventors & Inventions
- James Clapper: the intelligence chief born here Famous People
- James J. Brennan Notable People
- James J. Wood Notable People
- James J. Wood: two hundred forty patents Inventors & Inventions
- James M. Barrett Notable People
- James R. Clapper Jr. Notable People
- James Rhea Notable People
- James Worden Notable People
- Jaylon Smith Notable People
- Jean Baptiste de Richardville Notable People
- Jean Baptiste Richardville and the Treaty-Era Fortune Great Fortunes
- Jean François Hamtramck Notable People
- Jeff Hammerbacher Notable People
- Jeff Hammerbacher: Facebook's data team, then Cloudera Dot-Com Era
- Jefferson Middle School Schools & Colleges
- Jefferson Pointe: the lifestyle center Malls & Shopping
- The Jefferson Theatre: the house that turned around Theaters
- Jenna Fischer Notable People
- Jenna Fischer: a birth tie, printed at its size Comedy
- Jenna Fischer: a producer's credit on The Office Film & TV Producers
- Jenna Fischer: born here, Pam Beesly to the world Famous People
- Jenney Electric → General Electric Businesses
- Jenney Electric → General Electric Notable People
- The Jenney works and the General Electric century Technology
- Jesse Greene and the News and Sentinel's War on the Klan Newspapers & Media
- Jesse Grice Notable People
- Jesse L. Williams Notable People
- Jessie Hamilton (1865–1960) — artist, and the Hamilton sisters Notable People
- Jill Bennett: the web-series producer who brought her feature home Film & TV Producers
- Jim Ash and Tim Ash — the brokerage general agency Founders & CEOs
- Jim Leonard: from The Diviners to three network series Film & TV Producers
- Jitneys, gasoline, and the law of the street Automobiles
- Joel Fremion (b. 1952) — fabric-collage artist Notable People
- Joel Roberts Ninde (1874–1916) — architect Notable People
- Joel Welty Notable People
- John A. Shoaff and the Shoaff Building Photographers
- John B. Franke — the baker who gave the city a park Founders & CEOs
- John Chapman Notable People
- John Claus Peters Notable People
- John Collias: a thousand distinguished citizens Artists
- The John D. Haynes House (1952) — Frank Lloyd Wright's Fort Wayne Usonian Architecture
- John Deere here: a facility claim tested, and the dealer on Lima Road Tractors
- John F. Wing (1852–1947) and Marshall S. Mahurin (1857–1939) — Wing & Mahurin, architects Notable People
- John Francis Noll Notable People
- John H. Aiken Notable People
- John H. Bass Notable People
- John H. Bass: Iron, Car Wheels, and Brookside Great Fortunes
- John Henry Holland Notable People
- John Hrehov (b. 1958) — painter Notable People
- John J. Tokheim and Ralph F. Diserens — the pump company that was moved here Founders & CEOs
- John Morris Notable People
- John Nuckols — first African American man on City Council Government
- John S. Irwin Elementary School Schools & Colleges
- John W. Dawson Notable People
- John Zelt Notable People
- Johnny Appleseed & Folklore Section
- Johnny Appleseed died in Fort Wayne and lies under the marker in Johnny Appleseed Park. Famous Stories & the Record
- The Johnny Appleseed Festival: history a child can eat Kids & Family Entertainment
- Johnny Appleseed's Grave and Johnny Appleseed Memorial Park Famous Landmarks
- Johnny Appleseed: the folk hero who died here, and lies here Famous People
- Jones, Bass & Company → Bass Foundry & Machine Works Businesses
- Jones, Bass & Company → Bass Foundry & Machine Works Notable People
- Joseph Corcoran · two trials, and the execution that ended a fifteen-year pause Notable Murder Cases
- Joseph F. Zurbuch Notable People
- Josiah Harmar Notable People
- The Journal Gazette Is Made — 1899 and the Locally Owned Morning Paper Newspapers & Media
- The Journalists Newspapers & Media
- The judges — Gull, Davis and Surbeck; Lee and Brady in the federal court Public Servants
- Julia Barr Notable People
- Julia E. Emanuel Notable People
- Julia M. Baker Stapleford and Wah-see-ola (1905) Authors & Books
- June Peppas: the Fort Wayne girl who won the last game ever played Sports Players
- Junior Achievement of Northern Indiana Charities
- Just Neighbors: the interfaith shelter Churches & Religion