If You Liked Percy Jackson....
Artemis Fowl series by Eoin Colfer
Athena the Brain by Joan Holub
Bartimaeus trilogy by Jonathan Stroud
Beyond the Deepwoods by Paul Stewart
Children of the Lamp: The Akhenaten Adventure by Phillip Kerr
Children of Fire by Laurence Yep
Corydon and the Island of Monsters by Tobias Druitt
Cronus Chronicles by Anne Ursu
The Dark Is Rising series by Susan Cooper
Julie Dove, Queen of Love by Bruce Coville
Gods of Manhattan series by Scott Mebus
Gregor the Overlander series by Suzanne Collins
Hound of Rowan by Henry Neff
Ingo by Helen Dunmore
Inkheart series by Cornelia Funke
Iris Messenger by Sarah Deming
Kane Chronicles: The Red Pyramid by Rick Riordan
The Last Apprentice series by Joseph Delaney
Magyk series by Angie Sage
Medusa Jones by Ross Collins
Midnight for Charlie Bone by Jenny Nimmo
The Mysterious Benedict Society series by Trenton Lee Stewart
Pandora Gets Jealous by Carolyn Hennesy
Runemarks by Joanne Harris
Savvy by Ingrid Law
Secret of the Sirens by Julia Golding
The Shadow Thieves by Anne Ursu
Skulduggery Pleasant by Derek Landy
Spellbinder by Helen Stringer
Nonfiction
D'Aulaire's Book of Greek Myths by Ingri D'Aulaire
Gods, Goddesses, and Monsters by Sheila Keenan
Have a Hot Time, Hades! by Kate McMullan
Mythology by Hestia Evans