Series beginning with U
- Uglies Trilogy
- Ulysses Moore
- Umbrella Mouse
- Unbelievable Fib
- Unbelievable Oliver
- Uncle Gobb
- Uncle Pete
- Uncle Shawn and Bill
- Uncommoners
- Undead
- Undead Pets
- Under Their Skin
- Underdogs
- Underland Chronicles
- Underworld Chronicles
- Unearthly Trilogy
- Unfamiliar Trilogy
- Unforgettable Logan Foster
- Unicorn Academy
- Unicorn Diaries
- Unicorn in New York
- Unicorn Magic
- Unicorn Magic - Series 2
- Unicorn Magic - Series 3
- Unicorn Magic - Series 4
- Unicorn Magic Specials
- Unicorn Princesses
- Unicorn Quest
- Unicorn Rescue Society
- Unicorn School
- Unicorn Seekers
- Unicorne Files
- Unicornia
- Unicorns of Blossom Wood
- Unintentional Adventures of the Bland Sisters
- Unipiggle the Unicorn Pig
- Unknown Assassin (USA)
- Unleashed
- Unlikely Exploits
- Unmapped Chronicles
- Unremembered
- Unwanted Quests
- Unwanteds
- UnWind Dystology
- Upside Down Magic
- Upside Down River
- Urban Outlaws
- Utterly Dark