List of former members of the United States House of Representatives (O) Number of years/terms representative/delegate has served Number of years/terms representative/delegate has served

| Representative | Years | State_ | Party | Lifespan |
|---|---|---|---|---|
| David J. O`Connell | 1919–1921 1923–1930 | New York | Democratic | 1868–1930 |
| Jeremiah E. O`Connell | 1923–1927 1929–1930 | Rhode Island | Democratic | 1883–1964 |
| Jerry J. O`Connell | 1937–1939 | Montana | Democratic | 1909–1956 |
| John Matthew O`Connell | 1933–1939 | Rhode Island | Democratic | 1872–1941 |
| Joseph F. O`Connell | 1907–1911 | Massachusetts | Democratic | 1872–1942 |
| Charles O`Connor | 1929–1931 | Oklahoma | Republican | 1878–1940 |
| James O`Connor | 1919–1931 | Louisiana | Democratic | 1870–1941 |
| James F. O`Connor | 1937–1945 | Montana | Democratic | 1878–1945 |
| John J. O`Connor | 1923–1939 | New York | Democratic | 1885–1960 |
| Michael P. O`Connor | 1879–1881 | South Carolina | Democratic | 1831–1881 |
| Caroline O`Day | 1935–1943 | New York | Democratic | 1875–1943 |
| James O`Donnell | 1885–1893 | Michigan | Republican | 1840–1915 |
| Charles T. O`Ferrall | 1884–1893 | Virginia | Democratic | 1840–1905 |
| James M. E. O`Grady | 1899–1901 | New York | Republican | 1863–1928 |