- O'BRIEN, Anna W.
- O'BRIEN, John
- O'BRIEN, Mary Frances (?-?)
- OCHEKE, Edgar (?-?)
- O'CONNOR, Rose Marie
- O'DELL, Millard C.
- OESTERLE, Richard
- OGLESBEE, Thurman Woodson
- OHE, Frank A.
- OLIN, Ella (1886-)
- OLIN, Nels O.
- OLINGER, Clara Edith (1883-1945)
- OLINGER, William Henry
- OLSCH, Rube
- OLSON, Hannah
- OMAN, Maude E.
- O'NEAL, William Eugene
- OREN, Bertha (1917-?)
- OREN, Florence (1912-1992)
- OREN, George William (1917-2014)
- OREN, Herbert C. (1925-?)
- OREN, Inez Emily Pearl (1916-?)
- OREN, Mary Nancy Addie (1922-1986)
- OREN, Meander Harrison (1887-1959)
- OREN, Melvia Elvia (1930-2016)
- OREN, Nanette Etta (1926-2008)
- OREN, Orland (1920-?)
- OREN, Virgil Sherman (1916-?)
- OREN, William
- ORR, Joseph
- ORR, Louis (?-?)
- ORR, Malinda (1816-1897)
- OSBORN, Paul E. (?-?)
- OSBORN, Rebecca Ann
- OTT, Ernest E. (1916-1999)
- OTT, Ernst Albert
- OTT, Harry W. (1917-1984)
- OTT, Herman Albert (1890-1956)