- The O'Conors of Castle Conor, County Mayo: From "Tales from All Countries"Author: Anthony TrollopeLanguage: English
- The Oahu College at the Sandwich IslandsAuthor: Punahou SchoolLanguage: English
- The Oakdale AffairAuthor: Edgar Rice BurroughsLanguage: English
- The Oaths, Signs, Ceremonies and Objects of the Ku-Klux-Klan.: A Full Expose. By A Late MemberAuthor: AnonymousLanguage: English
- The Observations of HenryAuthor: Jerome K. (Jerome Klapka) JeromeLanguage: English
- The Obstacle RaceAuthor: Ethel M. (Ethel May) DellLanguage: English
- The Ocean and Its WondersAuthor: R. M. (Robert Michael) BallantyneLanguage: English
- The Ocean Cat's Paw: The Story of a Strange CruiseAuthor: George Manville Fenn, W. S. (Walter S.) StaceyLanguage: English
- The Octopus : A Story of CaliforniaAuthor: Frank NorrisLanguage: English
- The Odd WomenAuthor: George GissingLanguage: English
- The Odds: And Other StoriesAuthor: Ethel M. (Ethel May) DellLanguage: English
- The Odes and Carmen Saeculare of HoraceAuthor: Horace, 66 BCE-9 BCE, John ConingtonLanguage: English
- The Odes of Casimire, Translated by G. HilsAuthor: Maciej Kazimierz Sarbiewski, Roestvig, Maren-Sofie [Commentator], Hils, G. [Translator]Language: English
- The OdysseyAuthor: Homer, Alexander PopeLanguage: English
- The Odyssey: Rendered into English prose for the use of those who cannot read the originalAuthor: Homer, Samuel ButlerLanguage: English
- The Odyssey of HomerAuthor: Homer, S. H. (Samuel Henry) Butcher, Andrew LangLanguage: English
- The Odyssey of HomerAuthor: Homer, William CowperLanguage: English
- The Old Apple Dealer (From "Mosses from an Old Manse")Author: Nathaniel HawthorneLanguage: English
- The Old Bachelor: A ComedyAuthor: William Congreve, G. S. (George Slythe) StreetLanguage: English
- The Old Bell of Independence; Or, Philadelphia in 1776Author: Henry C. (Henry Clay) WatsonLanguage: English
- The Old Bush SongsAuthor: A. B. (Andrew Barton) PatersonLanguage: English
- The Old Castle and Other StoriesAuthor: AnonymousLanguage: English
- The Old Coast Road: From Boston to PlymouthAuthor: Agnes RotheryLanguage: English
- The Old Curiosity ShopAuthor: Charles DickensLanguage: English
- The Old English Baron: a Gothic StoryAuthor: Clara ReeveLanguage: English
- The Old English PhysiologusAuthor: Albert S. (Albert Stanburrough) Cook, Cynewulf, James Hall PitmanLanguage: English
- The Old Flute-Player: A Romance of To-dayAuthor: Edward Marshall, Charles Turner Dazey, Hare, J. Knowles [Illustrator], Clarence RoweLanguage: English
- The Old Folks' Party: 1898Author: Edward BellamyLanguage: English
- The Old Franciscan Missions Of CaliforniaAuthor: George Wharton JamesLanguage: English
- The Old Front LineAuthor: John MasefieldLanguage: English
- The Old Gray HomesteadAuthor: Frances Parkinson KeyesLanguage: English
- The Old HomesteadAuthor: Ann S. (Ann Sophia) StephensLanguage: English
- The Old Man in the CornerAuthor: Orczy, Emmuska Orczy, BaronessLanguage: English
- The Old Man of the Sea: Ship's Company, Part 11.Author: W. W. (William Wymark) Jacobs, Will OwenLanguage: English
- The old man's bagAuthor: T. W. H. (Thomas William Hodgson) Crosland, Monsell, J. R. [Illustrator]Language: English
- The Old Manse (From "Mosses from an Old Manse")Author: Nathaniel HawthorneLanguage: English
- The Old Masters and Their Pictures, For the Use of Schools and Learners in ArtAuthor: Sarah TytlerLanguage: English
- The Old Merchant Marine: A Chronicle of American Ships and SailorsAuthor: Ralph Delahaye PaineLanguage: English
- The Old Northwest: A Chronicle of the Ohio Valley and BeyondAuthor: Frederic Austin Ogg, Allen JohnsonLanguage: English
- The Old Peabody Pew: A Christmas Romance of a Country ChurchAuthor: Kate Douglas Smith WigginLanguage: English
- The Old Roman World : the Grandeur and Failure of Its Civilization.Author: John LordLanguage: English
- The Old Santa Fe Trail: The Story of a Great HighwayAuthor: Henry Inman, Buffalo BillLanguage: English
- The Old Stone HouseAuthor: Constance Fenimore WoolsonLanguage: English
- The Old Stone House and Other StoriesAuthor: Anna Katharine GreenLanguage: English
- The Old Wives' TaleAuthor: Arnold BennettLanguage: English
- The Olden Time Series, Vol. 1: Curiosities of the Old Lottery: Gleanings Chiefly from Old Newspapers of Boston and Salem, MassachusettsAuthor: Henry M. (Henry Mason) BrooksLanguage: English
- The Olden Time Series, Vol. 3: New-England Sunday: Gleanings Chiefly From Old Newspapers Of Boston And Salem, MassachusettsAuthor: Henry M. (Henry Mason) BrooksLanguage: English
- The Olden Time Series, Vol. 4: Quaint and Curious Advertisements: Gleanings Chiefly from Old Newspapers of Boston and Salem, MassachusettsAuthor: Henry M. (Henry Mason) BrooksLanguage: English
- The Olden Time Series, Vol. 5: Some Strange and Curious Punishments: Gleanings Chiefly from Old Newspapers of Boston and Salem, MassachusettsAuthor: Henry M. (Henry Mason) BrooksLanguage: English
- The Olden Time Series, Vol. 6: Literary Curiosities: Gleanings Chiefly from Old Newspapers of Boston and Salem, MassachusettsAuthor: Henry M. (Henry Mason) BrooksLanguage: English
- The Olden Time Series: Vol. 2: The Days of the Spinning-Wheel in New England: Gleanings Chiefly from old Newspapers of Boston and Salem, MassachusettsAuthor: Henry M. (Henry Mason) BrooksLanguage: English
- The Oldest Code of Laws in the World: The code of laws promulgated by Hammurabi, King of Babylon, B.C. 2285-2242Author: Hammurabi, King of Babylonia, C. H. W. (Claude Hermann Walter) JohnsLanguage: English
- The Olynthiacs and the Phillippics of Demosthenes: Literally translated with notesAuthor: Demosthenes, Charles Rann KennedyLanguage: English
- The one great realityAuthor: Louisa Clayton, Evan Henry HopkinsLanguage: English
- The One Moss-RoseAuthor: Philip Bennett PowerLanguage: English
- The One Woman: A Story of Modern UtopiaAuthor: Dixon, Thomas, Jr.Language: English
- The Online WorldAuthor: Odd De PresnoLanguage: English
- The Onlooker, Volume 1, Part 2Author: Various, Alfred Henry LewisLanguage: English
- The Only True Mother Goose MelodiesAuthor: AnonymousLanguage: English
- The Ontario High School ReaderAuthor: Marty, Aletta E.Language: English