| One Pitch Away | Sowell, Mike | "Sports"
| 320 | 1995 | 4 | 2025-06-06 |
| One Police Plaza | Caunitz, William J. | "Fiction - General"
| 371 | | 4 | 1989-09-12 |
| One Shot at Forever | Ballard, Chris | "Sports"
| 230 | 2012 | 6 | 2019-08-13 |
| One Summer | Bryson, Bill | "U.S. History - Cultural"
| 456 | 2013 | 7 | 2014-04-25 |
| Onions in the Stew | MacDonald, Betty | "Autobiographies, Memoirs and Biographies"
| 256 | 1955 | 6 | 2021-07-28 |
| Only Girl in the Game, The | MacDonald, John D. | "Fiction - Mystery"
| 224 | 1960 | 6 | 1990-04-15 |
| Only Yesterday | Allen, Frederick Lewis | "U.S. History - Cultural"
| 237 | 1931 | 8 | 1987-11-15 |
| Open Boat and Other Stories, The | Crane, Stephen | "Fiction - Short Story Collection"
| 0 | 1897 | 8 | |
| Open Horizons | Olson, Sigurd F. | "Nature/Science"
| 227 | 1969 | 8 | |
| Opening the Gospel of John | Hawley, Philip W. Comfort and Wendell C. | "Theology"
| 341 | 1994 | 6 | 2010-04-09 |
| Oranges | McPhee, John | "Nature/Science"
| 149 | 1966 | 7 | 2003-11-25 |
| Orchid Thief, The | Orleans, Susan | "Nature/Science"
| 282 | 1998 | 6 | 2004-09-20 |
| Oregon Trail, The | Buck, Rinker | "Travel"
| 416 | 2015 | 6 | 2016-02-14 |
| Oregon Trail, The | Parkman, Francis | "Travel"
| 286 | 1849 | 8 | 1995-11-12 |
| Original Water-Color Paintings for The Birds of America, The | Audubon, John James | "Nature/Science"
| 431 | 1838 | 8 | 0000-00-00 |
| Oroonoko | Behn, Aphra | "Fiction - General"
| 78 | 1688 | 7 | 1998-01-30 |
| Orphans Preferred | Corbett, Christopher | "U.S. History - Cultural"
| 255 | 2003 | 6 | 2004-08-31 |
| Orthodoxy | Chesterton, G.K. | "Theology"
| 299 | 1908 | 8 | 2003-03-01 |
| Osterman Weekend, The | Ludlum, Robert | "Fiction - Adventure"
| 336 | 1972 | 7 | |
| Othello | Shakespeare, William | "Drama"
| 91 | 1604 | 6 | 1996-03-26 |
| Other 637 Best Things Anybody Ever Said, The | Byrne, Robert | "Humor"
| 160 | | 7 | 1988-12-09 |
| Other Times, Other Worlds | MacDonald, John D. | "Fiction - S. F./Fantasy"
| 282 | 1978 | 6 | 1999-08-10 |
| Otley (ebay) | Waddell, Martin | "Fiction - Adventure"
| 0 | | | |
| Our American Cousin | Taylor, Tom | "Drama"
| 102 | 1851 | 9 | 1909-09-15 |
| Our Man in Havana | Greene, Graham | "Fiction - Adventure"
| 242 | 1958 | 7 | 1997-09-13 |
| Our Marvelous Native Tongue | Claiborne, Robert | "Literature/Essays"
| 307 | | 7 | 1994-09-11 |
| Our Murdered Presidents: The Medical Story | Brooks, Stewart M. | "U.S. History - Political"
| 202 | 1966 | 5 | 2000-07-30 |
| Our Mutual Friend | Dickens, Charles | "Fiction - General"
| 911 | 1865 | 10 | 1995-03-10 |
| Our Oriental Heritage | Durant, Will | "World History - Cultural"
| 385 | 1935 | 5 | 1997-08-21 |
| Our Smallest Towns | Kitchen, Dennis | "Travel"
| 111 | 1995 | 7 | 2000-01-04 |
| Our Town | Wilder, Thornton | "Drama"
| 143 | 1938 | 4 | 1992-09-13 |
| Our Vanishing Landscape | Sloane, Eric | "U.S. History - Cultural"
| 107 | 1955 | 9 | 1990-02-03 |
| Out of Africa | Dinesen, Isak | "Travel"
| 389 | 1937 | 8 | 1997-02-08 |
| Out of the Blackout | Barnard, Robert | "Fiction - Mystery"
| 182 | 1984 | 6 | 2007-11-09 |
| Out of the Silent Planet | Lewis, C.S. | "Fiction - S. F./Fantasy"
| 160 | 1938 | 7 | 1995-04-25 |
| Outbreak | Stier, Greg | "Theology"
| 260 | 2006 | 7 | 2007-01-27 |
| Outermost House, The | Beston, Henry | "Nature/Science"
| 218 | 1928 | 6 | 2021-11-25 |
| Outlander | Gabaldon, Diana | "Fiction - Historical"
| 850 | 1992 | 6 | 2023-05-14 |
| Outlaw | Haycox, Ernest | "Fiction - Short Story Collection"
| 0 | 1939 | | |
| Outlaw on Horseback | Ermine, Will | "Fiction - Western"
| 238 | 1946 | 5 | 2022-12-14 |
| Outlined, Galatians, The | Lee, Robert | "Theology"
| 115 | | 5 | 2010-09-17 |
| Outside Lies Magic | Stilgoe, John R. | "Reference/Miscellaneous"
| 187 | 1998 | 6 | 1999-07-09 |
| Over Seventy (watch) | Wodehouse, P.G. | "Literature/Essays"
| 0 | 1957 | | |
| Over the Earth I Come | Schultz, Duane | "U.S. History - Military"
| 284 | 1992 | 8 | 2001-09-09 |
| Over Washington | Morgan, Murray | "Art/Photography"
| 254 | 1989 | 6 | 2000-03-04 |
| Overcoat and Other Stories, The | Gogol, Nikolai | "Fiction - Short Story Collection"
| 0 | 1841 | 6 | |
| Owl At Home | Lobel, Arnold | "Fiction - Chapter Books"
| 64 | 1975 | 7 | 2007-03-14 |
| Owls of the Eastern Ice | Slaght, Jonathan C. | "Nature/Science"
| 314 | 2020 | 6 | 2023-03-27 |
| Ox-Bow Incident, The | Clark, Walter Van Tilburg | "Fiction - Western"
| 224 | 1940 | 7 | |
| Ox-Team Days on the Oregon Trail | Meeker, Ezra | "U.S. History - Cultural"
| 142 | 1922 | 7 | 2022-10-02 |
