- O diário da irmã de Laura
- O menino no alto da montanha
- O mistério da ilha de D. João VI
- O mundo onde o tempo parou
- O Nascimento dos Deuses: Romance de Tutankhâmon
- O ovo do elefante
- O Paradoxo 99
- O telephone
- O the Red Rose Tree
- Oakland Tales
- Oath Breaker
- Oath of Deception
- Oath of Destruction
- Oblomov
- Obsidian and Stars
- Oceans of Red: Demon Revolution
- Ocell blanc
- Odhin's Trost - Ein nordischer Roman aus dem elften Jahrhundert
- Odhin's Trost: Historischer Roman
- ODIN'S PROMISE
- Odin's Promise: A Novel of Norway
- Odins Schwert
- Odysseus pojke
- Of Gods, Goddesses, Temples and Priests - Ancient Egypt History Facts Books Children's Ancient Hist...
- Offside
- Og
- Oh, Freedom!
- Ohne den Vater: Erzählung aus dem Kriege
- Okami
- Old Mortality
- Old Mortality (Unabridged)
- Old West History for Kids - Settlement of the American West (Wild West) US Western History 6th Gra...
- Oleg oder Die belagerte Stadt
- Oliver y Max
- Olivia Twist
- Olivia Twist Educator's Guide
- Olmec Civilization for Kids - History and Mythology America's First Civilization 5th Grade Social ...
- On Blood Road (a Vietnam War novel)
- On Her Majesty's Secret Service
- On Midnight Beach
- On the Irrawaddy
- On Track for Treasure
- Once Upon a Crime
- Once Upon a Summer
- Once Upon a Time Long, Long Ago
- Once Upon Two Kingdoms
- One April in Boston
- One Came Home
- One Day in Oradour
- One Is One
- One of the 28th
- One Small Step
- One-Eyed Cat
- Onkel Toms Hütte
- Only Remembered
- Only the Stars Know Her Name
- Open My Eyes
- Open Werther
- Operation Clean Sweep
- Opus Gemini III
- Orage sur le Val d'Hespar
- Oran 62 : La rupture
- Orlando
- Orlando furioso
- Oroonoko
- Orphan, Monster, Spy
- Orphans' Inn
- Oryn ou la légende du Peuple de l'eau
- Os anjos contam histórias
- Otherwise Known as Possum
- Otto of the Silver Hand
- Otto P. Nudd
- Our Australian Girl
- Our Australian Girl: Marly walks on the Moon (Book 4)
- Our Australian Girl
- Our Australian Girl: Marly walks on the Moon (Book 4)
- Our Australian Girl: Marly's Business (Book 2)
- Our Australian Girl: Meet Marly (Book 1)
- Our Australian Girl: Meet Pearlie (Book 1)
- Our Little Arabian Cousin
- Our Little Brazilian Cousin
- Our Little Czecho-Slovak Cousin
- Our Little Danish Cousin
- Our Little Dutch Cousin
- Our Little English Cousin
- Our Little French Cousin
- Our Little German Cousin
- Our Little Hindu Cousin
- Our Little Japanese Cousin
- Our Little Norman Cousin of Long Ago
- Our Little Persian Cousin
- Our Little Porto Rican Cousin
- Our Little Siamese Cousin
- Our Little Swiss Cousin
- Our Only May Amelia
- Our Other Lives
- Our Young Folks
- Out of Darkness
- Out of the Blue
- Out of the Dust (Scholastic Gold)
- Out of the Easy
- Out of the Hitler Time trilogy: When Hitler Stole Pink Rabbit, Bombs on Aunt Dainty, A Small Person ...
- Out Of The Silent Planet
- Out of Tune
- Outbreak (The 39 Clues: Superspecial)
- Outcast: Keepers of the Stone Book One
- Outlaw
- Outpost in Time
- Ovejas Perdidas
- Over the River