O
- Oak View Elementary School Schools & Colleges
- Oakdale Neighborhoods
- The Odd Fellows: sick benefits from 1844 Lodges & Fraternal Orders
- The Odyssey — invented elsewhere, engineered here, built in Tennessee Technology
- The official election returns Sources
- Olaf N. Guldlin Notable People
- The Old Apple Tree, which no one can place Historical Mysteries
- The Old City Hall (1893) — Wing & Mahurin's Sandstone City Building Architecture
- The Old Fort — Lantern Tours and a Borrowed Horseman Ghost Stories
- The Old Fort as an open-air museum Museums
- The Old Fort on Spy Run is Anthony Wayne's fort. Famous Stories & the Record
- The Old Fort Replica — 1201 Spy Run Avenue Famous Landmarks
- Old National Bank in Fort Wayne Businesses
- The Olds Family: Wagon Wheels for a Continent Great Fortunes
- Olds' Wagon Works — after 1900 Businesses
- One building of nine: the Arts United Center opens, 1973 Culture
- One Summit Square / Indiana Michigan Power Center (1982) — Kevin Roche's Tower Architecture
- One Year of Abolition — the Fort Wayne Standard, 1854–1855 Newspapers & Media
- One-room schools and the township trustees Schools & Colleges
- The Orangutans: Tengku, Tara, Asmara, Raya Zoo
- Orchard Ridge Country Club Private Clubs
- An orchestra twice-born: 1924, 1933, 1944 Culture
- Orff's Mill (the Edsall Mill, Empire Mill, the Old Stone Mill) Businesses
- The organizing record · the NAACP, the clubs, and Dr. King's visit Black History
- The Original Plat as a Map, 1824 Historic Maps
- The Ossian shell companies Lottery & Crypto
- The Other Baptist Churches: Immanuel, South Wayne, Union Churches & Religion
- The other Columbia Street: the clearance of 1966 Historic Preservation
- The other historic congregations · Pilgrim, Mount Olive and Union, True Love Black History
- The Other Presbyterian Churches: Westminster, Third, Bethany, Westfield Churches & Religion
- The other reserves on and around this ground Land Treaties & Titles
- The other side of the ledger: the bust, and what it took Dot-Com Era
- The Other Signals — WGL, WKJG Radio, FM, and Public Radio Newspapers & Media
- Our Lady of Good Hope School Schools & Colleges
- “Our Murderers” · the docket the Sentinel counted in November 1875 Notable Murder Cases
- The Oyster Bar: a saloon table since 1888 Food & Restaurants