- Open Minds
- Open Thy Heart
- Opening
- Operación Ancla
- Operación Ave
- Operación Beowulf
- Operación cliché
- Operación Demonio
- Operación Escudo
- Operación Pelusa
- Operación San Valentín
- Operación Águila
- Operatic Duck / Duck On Tour
- Operation Absolution
- Operation Beautiful
- Operation Cat Tale
- Operation Clean Sweep
- Operation Eiffel Tower
- Operation Falkenstein und die Angst vor dem Unbekannten
- Operation Frog Effect
- Operation Gemsbok
- Operation Get Rid of Mom's New Boyfriend
- Operation Homecoming Queen
- Operation Ice Maker
- Operation Josh Taylor
- Operation Normal
- Operation Prom Date
- Operation Pucker Up
- Operation Red
- Operation S.O.S.
- Operation Sasquatch
- Operation Stargazer
- Operation Stargazer
- Operation Stay in England
- Operation: Blueberry Pancake
- Operation: Containment
- Operation: Dump the Chump
- Operation: Montauk
- Operation: Save Halloween
- Operation: Save Santa
- Operation: Survival
- Operazione controspionaggio
- Operazione Cristopher
- Operazione N.O.N.N.O.
- Operação Cambess
- Opere. Viaggio notturno. Mozart. La conversione di Ratisbonne (con note e espansione online)
- Opfør dig ordentligt, og vær en god ven
- Opgøret
- Ophelia After All
- Ophelia and the Marvelous Boy
- Opie Jones and the Superhero Slug
- Opie Jones Talks to Animals
- Opostos
- Opowiastki świąteczne
- Opowieści niezwykłe
- Opowieści o małej czarownicy Ismie
- Opowieści o uczuciach
- Opowieści wigilijne 2. Świerszcz za kominem
- Oppdrag abort
- Opposing Sides
- Opposite Island
- Oppositecy Prophecy
- Opposition (Saga LUX 5)
- Oppressed An Arelia LaRue Novel #4
- Oprøret i Budapest
- Opstandeling, Pion, Koning (Over Kronen en Glorie—Boek 4)
- Optimists Die First
- Option Four
- OPUS - Das verbotene Buch
- OPUS - Die Bücherjäger
- Opus Gemini III
- Opus Poemador
- Opération "Maurice"
- Opération Dreamteam
- Opération Jehanne d'Arc
- Opération Léviathan
- Opération Manchots - Lecture roman jeunesse aventure écologie animaux - Dès 9 ans
- Opération Pantalon
- Opération vide-grenier - Ebook
- Opération Vox
- Opętana (Część 12 Wampirzych Dzienników)
- Or the Girl Dies
- Ora lo sai
- Oracle of Doom (The Library Book 3)
- Oracles of Delphi Keep
- Oracles' Tale
- Orage sur le Val d'Hespar
- Orage, petit seigneur des ténèbres - Lecture roman jeunesse conte - Dès 8 ans
- Oraklets gåta
- Oran 62 : La rupture
- Orang Ketiga
- Orange Animals On The Planet
- Orange Crush
- Orange Fairytales