| Calvin Monroe O'BANION (1854-1926) | & | Mary Jeanette McCray LEE (1861-1937) |
| Claude Duval O'BANION (1884-1948) | & | Asberine Agnes CASSIDAY (1892-1945) |
| Evan O'BANION (1799-1874) | & | Margaret HALL (1801-????) |
| Evan O'BANION (1799-1874) | & | Mary Ann COLE (1823-1896) |
| Evan O'BANION (1799-1874) | & | Jane Hawley BOOTH (1821-1895) |
| Evan O'BANION (1799-1874) | & | Melinda SMITH (1824-????) |
| Evan O'BANION (1799-1874) | & | Nancy ALLEN (????-????) |
| James O'LEARY (1851-1920) | & | Mary Elizabeth KEATING (1855-1924) |
| Armor Virgil OAKES (1896-1969) | & | Clara Alice WILLIAMSON (1893-1973) |
| Odd ODSON (1814-1906) | & | Carry KNUDSON (1820-1884) |
| Alfred Joseph OGLE (1826-1874) | & | Roxanna Elizabeth STARNES (1833-1900) |
| Jacob Stecher OHLSEN (1873-????) | & | Louisa BOCKWOLDT (1879-1968) |
| Ole L. OLESON (1842-1930) | & | Anne Maria Olsdatter HANSON (1851-1928) |
| Eric OLSON (????-1951) | & | Sarah Sylvia BOATWRIGHT (1876-????) |
| Andrew OLSON (1867-1947) | & | Ana Marie 'Mollie' JOHNSON (1872-1957) |
| James Leonard OLSON (1946-????) | & | Denise SMITHART (1960-????) |
| Casper W. OPPOLD (????-1981) | & | Catherine E. ENGEL (????-1975) |
| Elijah ORAHOOD (1798-1860) | & | Rachel "Sarah" CARTER (????-1835) |
| Elijah ORAHOOD (1798-1860) | & | unknown (????-????) |
| Elijah ORAHOOD (1798-1860) | & | Lucy WAYNE (1811-1860) |
| Jacob ORAHOOD (1804-1873) | & | Priscilla GARRET (1806-1860) |
| Thomas ORAHOOD (1798-1860) | & | Elizabeth Ann FISK (1814-1880) |
| Aaron ORCHARD (1810-1874) | & | Mary Jane HARPER (1812-1855) |
| Moses ORCHARD (1807-1898) | & | Sarah Marcia IRELAND (1805-1873) |
| Ephraim L. ORR (1831-1910) | & | Melissa A. WEEKS (1843-1875) |
| Franklin Foster ORR (1890-1964) | & | Gertrude Marie LINEBACK (1895-1957) |
| Thor [Thaulow] ORSTAD (1862-1931) | & | Marie Bertha HOKENSON (1869-1927) |
| Ernest Perry OWENS (1911-2002) | & | Dorothy Arlene TURPEN (1916-1973) |
| Mathew Henry OWENS (1822-1902) | & | Eveline SNELSON (1828-1867) |
| Melville Lee OWENS (1877-1928) | & | Margaret Elen RHOADES (1867-1955) |