- Obsidian Blade
- Obsidian Castle: Der letzte Kristallsplitter
- Obsidian Heart (The Sisters with the Glass Hearts & Jet Black heart (5SOS))
- Obsidio
- Obstacles
- Obstaclēs
- Obstinate
- Obstsammlerherz
- Obvious Isn't Obvious
- Obviously Horatio
- Obřad Mečů (Sága Čarodějův Prsten – Kniha Sedmá)
- Occam's Razor
- Occhi di Luna
- Occhi di sale
- Occhio al pidocchio!
- Occult & Supernatural Tales
- OCD Love Story
- OCD, The Dude, and Me
- OCDaniel
- Ocean Adventures with Elwar the Dolphin
- Ocean Blue
- Ocean Breeze
- Ocean Child
- Ocean City - Tome 2 - Dans la cachette des rebelles
- Ocean City – Im Versteck des Rebellen
- Ocean City – Jede Sekunde zählt
- Ocean City – Stunde der Wahrheit
- Ocean Commotion
- Ocean Depths
- Ocean Heart
- Ocean of Memories
- Ocean Pearl
- Ocean Rules: The Bikini Collective
- Ocean so Wide
- Ocean View Terrace
- Ocean View Terrace and the Blue Pirate Eater
- Oceanblue
- Oceanborn
- Oceanborn (The Aquarathi, Book 2)
- Oceanheart
- Oceania T1 : la prophétie des oiseaux
- Oceania T2 : horizon blanc
- Oceans of Love
- Oceans of Red: Demon Revolution
- Oceans of Red: Demon Revolution
- Ocell blanc
- Ocelové město
- Ocena własna sprawności fizycznej członków kadry narodowej karate
- Oceľová cesta
- Och allt blir återfött
- Och bingo är bara för de förlorade
- Ocho
- Ocho lugares que me recuerdan a ti (Nueva edición)
- Ocho Primos
- Ocolul pământului în optzeci de zile
- OCR A Level PE (Year 1 and Year 2)
- OCR A Level PE Book 1
- OCR A Level PE Book 2
- OCR A-level Physical Education Student Guide 1: Physiological factors affecting performance
- OCR A-level Physical Education Student Guide 2: Psychological factors affecting performance
- OCR A-level Physical Education Student Guide 3: Socio-cultural issues in physical activity and sport
- Octavious and His Busy Tentacles
- Octi the Octopus
- October Breezes Twin Pack
- Octopus's Garden
- Octovilian: Book Three of The Viridian Chronicles
- Oculta
- Oculto Poder
- Océane
- Odaát
- Odd
- Odd and the Frost Giants
- Odd et les géants de glace
- Odd Girl In
- Odd Tales - The Stopping of Harold
- Oddfellow's Orphanage
- Oddily
- Odds & Ends (The Odds Series #3)
- Odds in Templeton
- Ode
- Ode to Rebellion
- Odens Son: Skogen
- Odens Son: Skuggan
- Odessa
- Odessa Again
- Odessa Lace - Marea Mystic #1: The Mystery of the Gypsy Ring
- Odete e Osmar
- Odette s'en va-t-en guerre
- Odhin's Trost - Ein nordischer Roman aus dem elften Jahrhundert
- Odhin's Trost: Historischer Roman
- Odile and the pelican - Odile et le pélican
- Odile et le pélican / Odile and the pelican
- Odin Blew Up My TV!
- ODIN'S PROMISE
- Odin's Promise: A Novel of Norway
- Odin's Ravens
- Odin, Loki, Thor, and More Children's Norse Folktales
- Odins Fame
- Odins Memoiren
- Odins Schwert
- Odinsbarn. Ravneringene 1
- Odio el color rosa
- Odio el Rosa 3: Historia de Alan
- Odio el Rosa Historia de Dani 1
- Odio el Rosa Historia de Sara 1
- Odiosis
- Odisea del mole
- Odisea por el espacio inexistente
- Odiseea
- Odissea
- Odissea illustrata da Adolfo De Carolis
- Odissea nel futuro
- Odisseia
- Odisseia em quadrinhos
- Odjuret i labyrinten och andra grekiska myter
- Odjuret vaknar
- Odločitev
- Odnaleziona (Część 8 Wampirzych Dzienników)
- Odnaleźć siebie
- Odpowiednia dziewczyna
- Odriel's Heirs
- Odrodzeni
- Odvážná holka
- Odysseus in the Serpent Maze
- Odysseus pojke
- Odysseus: The Hero of Ithaca, adapted from the third book of the primary schools of Athens, Greece
- Odyssey of the Outcast
- Odyssée dans l'espace
- Oedipe le maudit
- Oeps...