List of authors by name: O
Abbreviations: ch = children's, d = drama, f = fiction, nf = non-fiction, p = poetry
A – B – C – D – E – F – G – H – I – J – K – L – M – N – O – P – Q – R – S – T – U – V – W – X – Y – Z \- Michelle Obama (born 1964, US, nf)
- Dositej Obradovi? (1739–1811, Habsburg E/Ottoman E, nf)
- Téa Obreht (born 1985, Yugoslavia/US, f/nf)
- Princess Anka Obrenovi? (1821–1868, Serbia, nf)
- Patrick O'Brian (1914–2000, England/Ireland, f), born Richard Patrick Russ
- Fitz James O'Brien (1828–1862, Ireland/US, f/p)
- John O'Brien (1878–1952, Australia, p/nf), pseudonym of Patrick Joseph Hartigan
- Robert C. O'Brien (1918–1973, US, f)
- Michael O'Brien (born 1948, Canada, f/nf)
- Mary-Louise O'Callaghan (living, Australia, nf)
- Thomas Occleve or Hoccleve (c. 1368–1426, England, p)
- Raquel Ochoa (born 1980, Portugal, f/nf)
- Elizabeth O'Conner (1913–2000, Australia, f/nf)
- Flannery O'Connor (1925–1964, US, f/nf)
- Mark O'Connor (p/nf)
- Mary-Anne O'Connor (living, Australia, f)
- Sakunosuke Oda (?????, 1913–1947, Japan, f/d/nf)
- Rosemary O'Day (born 1945, England, nf)
- Constance O'Day-Flannery (living, US, f)
- Scott O'Dell (1898–1989, US, f/ch)
- Alexandru Odobescu (1834–1895, Wallachia/Romania, f/nf)
- Laurel O'Donnell (living, US, f)
- Mietta O'Donnell (1950–2001, Australia, nf)
- Bernard O'Dowd (1866–1953, Australia, p/nf)
- Kenzabur? ?e (?????, born 1935, Japan, f/nf)
- Maggie O'Farrell (born 1972, N Ireland/England, f)
- Ernest O'Ferrall (1881–1925, Australia, p/f/nf)
- Y?ko Ogawa (????, born 1962, Japan, f/nf)
- Elisabeth Ogilvie (1917–2006, US, f/nf/ch)
- William Henry Ogilvie (1869–1963, Scotland, p/f)
- Ogiwara Seisensui (?????, 1884–1976, Japan, p)
- Dejan Ognjanovi? (born 1973, Yugoslavia/Montenegro)
- Vida Ognjenovi? (born 1941, Yugoslavia/Serbia, d/nf)
- Mushitaro Oguri (?????, 1901–1946, Japan, f)
- John O'Hara (1905–1970, US, f/d/nf)
- John Bernard O'Hara (1862–1927, Australia, p)
- Pixie O'Harris (1903–1991, Wales/Australia, nf/p/ch), pseudonym of Rhona Olive Harris
- Bruno K. Öijer (born 1951, Sweden, p)
- Bayo Ojikutu (born 1971, Nigeria/US, f)
- Okakura Kakuz? (????, 1863–1913, Japan, nf)
- Kanoko Okamoto (?????, 1889–1939, Japan, p/nf)
- Kido Okamoto (????, 1872–1939, Japan, d)
- Gabriel Okara (1921–2019, Nigeria, p/n)
- Janette Oke (born 1935, Canada, f)
- Nicolaus Olahus (1493–1568, Hungary, nf)
- John Olday (1905–1977, US/Australia, f)
- Jenny Oldfield (born 1949, England, ch)
- John Oldmixon (1673–1742, England, nf/p/d)
- Laurence Oliphant (1829–1988, S Africa/England, nf/f)
- Margaret Oliphant (1828–1897, Scotland/England, f/nf)
- Jamie Oliver (born 1975, England, nf)
- Narelle Oliver (1960–2016, Australia, ch)
- Carlos de Oliveira (1921–1981, Portugal, p/f)
- Juste Olivier (1807–1876, Switzerland, p/f/nf)
- Gregg Olsen (born 1959, US, nf/f)
- Albert Olsson (1904–1994, Sweden, f)
- Jan Olof Olsson (1920–1974, Sweden, nf)
- Grozdana Oluji? (1934–2019, Yugoslavia/Serbia, f/ch)
- Carola Oman (1897–1978, England, f/nf/ch)
- Ömer Seyfettin (1884–1920, Ottoman E, f/p)
- Michael Ondaatje (born 1943, Ceylon/Canada, p/f/nf)
- ?udo Ondrejov (1901–1962, Austria-Hungary/Czechoslovakia, p/f/nf)
- Alexandre O'Neill (1924–1986, Portugal, p)
- Eugene O'Neill (1888–1953, US, d/f)
- Beria Onger (1921–2015, Turkey, nf)
- Fuyumi Ono (?????, born 1960, Japan, f)
- Ono no Komachi (????, c. 825 – c. 900, Japan, p)
- Inte Onsman (1872–1929, Netherlands, d)
- Onyeka (living, England, nf)
- Makoto ?oka (???, 1931–2017, Japan, p/nf)
- Sh?hei ?oka (????, 1909–1988, Japan, f/nf)
- Amelia Opie (1769–1853, England, f/p/nf)
- Martin Opitz (1597–1639, Germany/Danzig, p)
- Kenneth Oppel (born 1967, Canada, ch)
- Joachim Oppenheim (1832–1891, Austria/Czech, nf)
- Robert Oppenheimer (1904–1967, US, nf)
- Leonard Oprea (born 1953, Romania/US, f/p/nf)
- Marek Oramus (born 1952, Poland, f/nf)
- Vladimir Oravsky (born 1947, Czechoslovakia/Sweden, d/ch)
- Mavro Orbini (1563–1614, Ragusa, nf)
- Baroness Orczy (1865–1947, Hungary/England, f/d)
- Orderic Vitalis (1075 – c.?1142, England, nf)
- Bill O'Reilly (born 1949, US, nf)
- Dowell O'Reilly (1865–1923, Australia, p/f)
- Jerry Ordway (born 1957, US, f/ch)
- Giorgio Orelli (1921–2013, Switzerland, p/nf)
- Giovanni Orelli (1928–2016, Switzerland, p/f/nf)
- Zaharije Orfelin (1726–1785, Habsburg E, nf/p)
- Mathieu Orfila (1787–1853, Spain/France, nf)
- Shinobu Orikuchi (????, 1887–1953, Japan, nf/f/p)
- István Örkény (1912–1979, Hungary, d/f)
- Milan Orli? (born 1962, Yugoslavia/Serbia, p/nf)
- Kate Orman (born 1968, Australia, f)
- Mary Orr (1910–2006, US, f)
- Garcia de Orta (c. 1501–1568, Portugal, nf)
- José Ortega y Gasset (1883–1955, Spain, nf)
- Abraham Ortelius (1527–1598, Netherlands, nf)
- Ramalho Ortigão (1836–1916, Portugal, nf)
- Ernst Ortlepp (1800–1864, Germany, p)
- Joe Orton (1933–1967, England, d/f/nf)
- George Orwell (1903–1950, England/Scotland, f/nf), pseudonym of Eric Arthur Blair
- Eliza Orzeszkowa (1841–1910, Russian E, f/nf)
- Kaoru Osanai (????, 1881–1928, Japan, d)
- Arthur Osborne (1906–1970, UK, nf)
- John Osborne (1929–1994, England, d)
- Mary Pope Osborne (born 1949, US, ch)
- Tam O'Shaughnessy (born 1952, US, ch)
- Pat O'Shea (1931–2007, Ireland/England, ch)
- Shunr? Oshikawa (????, 1876–1914, Japan, f/nf)
- Andreas Osiander (1498–1552, Germany, nf)
- Ana de Castro Osório (1872–1935, Portugal, nf)
- Ferdynand Antoni Ossendowski (1876–1945, Russian E/Poland, nf)
- Carl von Ossietzky (1889–1938, Germany, nf)
- Klas Östergren (born 1955, Sweden, f/d)
- Josip Osti (born 1945, Yugoslavia/Slovenia, p/nf)
- John Ostrander (born 1949, US, ch)
- Niyi Osundare (born 1947, Nigeria, p/d/nf)
- Oswald von Wolkenstein (1336/1337–1445, Germany, p)
- Mizuho ?ta (????, 1876–1955, Japan, p/nf), pseudonym of Teiichi ?ta (???)
- Otfrid of Weissenburg (c. 800–870, Germany, p)
- ?tomo no Yakamochi (????, c. 718–785, Japan, p)
- Géza Ottlik (1912–1990, Hungary, nf)
- Ouida (1839–1908, England/Italy, f/ch/nf), pseudonym of Maria Louise Ramé
- Ouyang Xiu (???, 1007–1072, China, nf/p)
- Ouyang Xun (???, 557–641, China, f)
- Ouyang Yu (???, born 1945, China/Australia, p/f/nf)
- Caroline Overington (born 1970, Australia, f/nf)
- Thomas Overbury (1581–1613, England, p/nf)
- Ovid (43 BC–AD 17/18, Roman E, p)
- Owain Owain (1929–1993, Wales, f/p)
- Robin Llwyd ab Owain (born 1959, Wales, p)
- Daniel Owen (1836–1895, Wales, f)
- David Owen (1795–1866, Wales, nf), pseudonym Brutus
- David Owen (Dewi Wyn o Eifion) (1784–1841, Wales, p)
- Gerallt Lloyd Owen (1944–2014, Wales, p)
- Goronwy Owen (1723–1769, Wales/US, p)
- Jan Owen (born 1940, Australia, p)
- Robert Owen (1771–1858, Wales/England, nf)
- Ruth Owen (1885–1954, US, nf/ch)
- Wilfred Owen (1893–1918, England/France, p)
- William David Owen (1874–1925, Wales, f)
- Helen Oxenbury (born 1938, England, ch)
- Elsie J. Oxenham (1880–1960, England, ch)
- Johan Gabriel Oxenstierna (1750–1818, Sweden, p)
- Lauren Oyler (living, US, f)
- Amos Oz (1939–2018, Palestine/Israel, f/ch/nf)
- Ozaki H?sai (????, 1885–1926, Japan, p)
- Ozaki Kihachi (????, 1892–1974, Japan, p)
- Ozaki K?y? (????, 1868–1903, Japan, f/p)
- Jacques Ozanam (1640–1718, France, nf)
- Emine Sevgi Özdamar (born 1946, Turkey/Germany, f/nf)
- Ismet Özel (born 1944, Turkey, p/nf)
- Joshua Ozersky (1967–2015, US, nf)
- Cynthia Ozick (born 1928, US, f/nf)
- Hanna O?ogowska (1904–1995, Duchy of Warsaw/Poland, f/p)
- Yasujir? Ozu (?????, 1903–1963, Japan, d)