- Undead Worlds
- Undead Worlds 2
- Undefeated: Jim Thorpe and the Carlisle Indian School Football Team
- Undefined
- Undeniable
- Under a Dancing Star
- Under a Purple Moon
- Under a Red Sky
- Under a Starlit Sky
- Under Alex's Bed
- Under Amelia's Wing
- Under an Apricot Moon
- Under Control
- Under Copp's Hill
- Under dansk flag
- Under en himmel av glas
- Under Falling Skies
- Under Hill (Aos Si, #2)
- Under His Bed
- Under His Spell
- Under Jupiter
- Under kometens hale
- Under Michigan
- Under My Bed: Zipto Meets Dubious
- Under My Hat: Tales from the Cauldron
- Under Plum Lake
- Under Pressure
- Under Pressure With a Squash
- Under the African Sky
- Under the Arches
- Under the Bed Fred
- Under the Bottle Bridge
- Under the Chilian Flag
- Under the Cover of Snow the Royal Unicorns Book One
- Under the Egg
- Under the Flame Tree
- Under the Ghost Gum Tree
- Under the Green Hill
- Under the Influence
- Under The Light Of A Full Moon
- Under the Lilacs
- Under the Mermaid Angel
- Under the Microscope : Earth's Tiniest Inhabitants - Soil Science for Kids Children's Earth Science...
- Under the Milky Way
- Under The Moon
- Under the Moon Bundle
- Under the Mountain
- Under the Mountain Boxed Set: Books 1-3
- Under the Neon Glow
- Under The Never Sky
- Under the Persimmon Tree
- Under the Rose Apple Tree
- Under the Rubble
- Under the Same Sky
- Under the Same Stars
- Under the Screaming Sky
- Under the Screaming Sky Book 1 Red Dragons
- Under the Sea
- Under the Shadow's Eye
- Under the Stars
- Under The Stars Of Faerie (Monkey Queen Book Three)
- Under the Summer Sun
- Under the Volcano
- Under the Water
- Under the Watsons' Porch
- Under the Waves
- Under trottoaren
- Under Western Eyes
- Undercover Fan
- Undercover Missions Operation Kursk K-141 Game Guide
- Undercover Princess
- Undercover Revenge
- Undercover Witch Academy: First Year
- Undercover Witch Academy: Second Year
- Undercover Witch Academy: Third Year
- Undercurrent
- Underdawgs
- Underdog
- Underground Cities
- Underground Railroad von Colson Whitehead (Lektürehilfe)
- Underground Time by Delphine de Vigan (Book Analysis)
- Underland
- Underlondon - Tome 1
- Underlondon - Tome 2
- Underlord
- Underminity
- Underneath Everything
- Underneath the Sea
- Underpants are Awesome! Three Pants-tastic Books in One!
- Underrail Game Guide