| O Keeffe, Georgia | (1887 - 1986) | 2 | Zitate |
| Obama, Barack | (*1961) | 12 | Zitate |
| Oberth, Hermann | (1894 - 1989) | 2 | Zitate |
| Ode, Erik | (1910 - 1983) | 1 | Zitat |
| Oehler, Wilhelm Johannes | (1877 - 1966) | 5 | Zitate |
| Oelsnitz, Dietrich | (*1964) | 1 | Zitat |
| Oertzen, Jaspar | (1912 - 2008) | 1 | Zitat |
| Oesch, Emil | (1894 - 1974) | 1 | Zitat |
| Oeser, Adam Friedrich | (1717 - 1799) | 1 | Zitat |
| Oetinger, Friedrich Christoph | (1702 - 1782) | 1 | Zitat |
| Oetker, Rudolf-August | (1916 - 2007) | 2 | Zitate |
| Oettinger, Eduard Maria | (1808 - 1872) | 1 | Zitat |
| Offenbach, Jacques | (1890 - 1980) | 2 | Zitate |
| Öger, Vural | (*1942) | 1 | Zitat |
| Ogilvy, David MacKenzie | (1911 - 1999) | 5 | Zitate |
| OHare McCormick, Anne Elizabeth | (1882 - 1954) | 2 | Zitate |
| Oken, Lorenz | (1779 - 1851) | 2 | Zitate |
| Okri, Ben | (*1959) | 3 | Zitate |
| Olearius, Adam | (1603 - 1671) | 1 | Zitat |
| Olivier, Laurence Kerr | (1907 - 1989) | 1 | Zitat |
| Olson, Kenneth | (1926 - 2011) | 1 | Zitat |
| Omidyar, Pierre | (*1967) | 1 | Zitat |
| Onassis, Aristoteles | (1906 - 1975) | 13 | Zitate |
| Oncken, Johann Gerhard | (1800 - 1884) | 2 | Zitate |
| Opel, Adam | (1837 - 1895) | 1 | Zitat |
| Opitz, Martin | (1597 - 1639) | 3 | Zitate |
| Oppenheim, James | (1882 - 1932) | 1 | Zitat |
| Oppenheim, Meret | (1913 - 1985) | 1 | Zitat |
| Oppenheimer, Harry Frederick | (1908 - 2000) | 1 | Zitat |
| Oppenheimer, Robert | (1904 - 1967) | 2 | Zitate |
| Oranien-Nassau, Wilhelm | (1840 - 1879) | 1 | Zitat |
| Orwell, George | (1903 - 1950) | 9 | Zitate |
| Osborne, John James | (1929 - 1994) | 2 | Zitate |
| Osho | (1931 - 1990) | 4 | Zitate |
| Osler, William | (1849 - 1919) | 8 | Zitate |
| Ossietzky, Carl | (1889 - 1938) | 3 | Zitate |
| Ossietzky, Carl | (1889 - 1938) | 5 | Zitate |
| Österreich, Albrecht II. | (1298 - 1358) | 1 | Zitat |
| Österreich, Maria Theresia | (1717 - 1780) | 2 | Zitate |
| Ostrowski, Nikolai Alexejewitsch | (1904 - 1936) | 3 | Zitate |
| Ostwald, Wilhelm | (1853 - 1932) | 2 | Zitate |
| Oswald, Hugo | | 1 | Zitat |
| Otis, James | (1725 - 1783) | 4 | Zitate |
| Otto, Rudolf | (1869 - 1937) | 1 | Zitat |
| Otway, Thomas | (1652 - 1685) | 2 | Zitate |
| Ovid | (43 v. Chr. - 18) | 8 | Zitate |
| Owen, Richard | (1804 - 1892) | 1 | Zitat |
| Owen, Robert | (1771 - 1858) | 5 | Zitate |
| Oz, Amos | (1939 - 2018) | 2 | Zitate |
| O`Connell, Daniel | (1775 - 1847) | 1 | Zitat |