- Nuttie's FatherAuthor: Charlotte M. (Charlotte Mary) YongeLanguage: English
- O May I Join the Choir Invisible! and Other Favorite PoemsAuthor: George Eliot, Elizabeth Barrett Browning, Robert Browning, Percy Bysshe ShelleyLanguage: English
- O'Flaherty V.C.: A Recruiting PamphletAuthor: Bernard ShawLanguage: English
- Obiter Dicta: Second SeriesAuthor: Augustine BirrellLanguage: English
- Odd Charges: Odd Craft, Part 13.Author: W. W. (William Wymark) Jacobs, Will OwenLanguage: English
- Odd craft [complete]Author: W. W. (William Wymark) Jacobs, Will OwenLanguage: English
- Odd Man Out: Sailor's Knots, Part 6.Author: W. W. (William Wymark) Jacobs, Will OwenLanguage: English
- Oddsfish!Author: Robert Hugh BensonLanguage: English
- Of Captain MissionAuthor: Defoe, DanielLanguage: English
- Of Human BondageAuthor: W. Somerset (William Somerset) MaughamLanguage: English
- Old ChristmasAuthor: Washington IrvingLanguage: English
- Old Christmas: from the Sketch Book of Washington IrvingAuthor: Washington Irving, Randolph CaldecottLanguage: English
- Old Fires and Profitable Ghosts: A Book of StoriesAuthor: Arthur Quiller-CouchLanguage: English
- Old Friends: Essays in Epistolary ParodyAuthor: Andrew LangLanguage: English
- Old Gold: The Cruise of the "Jason" BrigAuthor: George Manville Fenn, Stanley L. WoodLanguage: English
- Old JackAuthor: William Henry Giles KingstonLanguage: English
- Old Lady Mary: A Story of the Seen and the UnseenAuthor: Mrs. (Margaret) OliphantLanguage: English
- Old Mortality, CompleteAuthor: Walter ScottLanguage: English
- Old Mortality, Volume 1.Author: Walter ScottLanguage: English
- Old Mortality, Volume 2.Author: Walter ScottLanguage: English
- Old Saint Paul's: A Tale of the Plague and the FireAuthor: William Harrison AinsworthLanguage: English
- Olive: A NovelAuthor: Dinah Maria Mulock Craik, G. (Georgina) BowersLanguage: English
- Oliver Goldsmith: A BiographyAuthor: Washington IrvingLanguage: English
- Oliver TwistAuthor: Charles DickensLanguage: English
- Oliver TwistAuthor: Charles DickensLanguage: French
- Olivia in IndiaAuthor: O. DouglasLanguage: English
- On Board the Esmeralda: Martin Leigh's Log - A Sea StoryAuthor: Hutcheson, John C. (John Conroy), William Heysham OverendLanguage: English
- On CompromiseAuthor: John MorleyLanguage: English
- On SomethingAuthor: Hilaire BellocLanguage: English
- On the Choice of BooksAuthor: Thomas Carlyle, Richard Herne ShepherdLanguage: English
- On the Irrawaddy: A Story of the First Burmese WarAuthor: G. A. (George Alfred) Henty, William Heysham OverendLanguage: English
- On the Pampas; Or, The Young SettlersAuthor: G. A. (George Alfred) HentyLanguage: English
- Once a weekAuthor: A. A. (Alan Alexander) MilneLanguage: English
- Once Aboard the Lugger-- The History of George and his MaryAuthor: A. S. M. (Arthur Stuart-Menteth) HutchinsonLanguage: English
- Onder Moeders VleugelsAuthor: Louisa May Alcott, G. W. (Gerardina Wilhelmina) ElbertsLanguage: Dutch
- One Day At ArleAuthor: Frances Hodgson BurnettLanguage: English
- One of Our Conquerors — CompleteAuthor: George MeredithLanguage: English
- One of Our Conquerors — Volume 1Author: George MeredithLanguage: English
- One of Our Conquerors — Volume 2Author: George MeredithLanguage: English
- One of Our Conquerors — Volume 3Author: George MeredithLanguage: English
- One of Our Conquerors — Volume 4Author: George MeredithLanguage: English
- One of Our Conquerors — Volume 5Author: George MeredithLanguage: English
- Orange and Green: A Tale of the Boyne and LimerickAuthor: G. A. (George Alfred) HentyLanguage: English
- Orley FarmAuthor: Anthony TrollopeLanguage: English
- Orpheus in Mayfair, and Other Stories and SketchesAuthor: Maurice BaringLanguage: English
- Oscar Wilde, His Life and Confessions — Volume 1Author: Frank HarrisLanguage: English
- OthelloAuthor: William ShakespeareLanguage: English
- OthelloAuthor: William ShakespeareLanguage: English
- OthelloAuthor: William ShakespeareLanguage: English
- OthelloAuthor: William ShakespeareLanguage: English
- OthelloAuthor: William Shakespeare, Christoph Martin WielandLanguage: German
- OthelloAuthor: William Shakespeare, Paavo Emil CajanderLanguage: Finnish
- OthelloAuthor: William Shakespeare, François GuizotLanguage: French
- Our American CousinAuthor: Tom TaylorLanguage: English
- Our Casualty, and Other Stories: 1918Author: George A. BirminghamLanguage: English
- Our Catholic Heritage in English Literature of Pre-Conquest DaysAuthor: Emily Henrietta HickeyLanguage: English
- Our Elizabeth: A Humour NovelAuthor: Florence A. (Florence Antoinette) Kilpatrick, Ernest ForbesLanguage: English
- Our Frank: and other storiesAuthor: Amy WaltonLanguage: English
- Our Friend the CharlatanAuthor: George GissingLanguage: English
- Our Mutual FriendAuthor: Charles DickensLanguage: English