9 books in series

Percy Jackson and the Olympians

Percy Jackson and the Olympians is a 11-book series with 9 released primary works first released in 1962 with contributions by Rick Riordan and Mary-Jane Knight.

The Lightning Thief
The Sea of Monsters
The Titan's Curse
Percy Jackson and the Bronze Dragon
The Battle of the Labyrinth
Percy Jackson and the Sword of Hades
The Last Olympian
The Chalice of the Gods
Wrath of the Triple Goddess
The Demigod Files
Percy Jackson & the Olympians: The Ultimate Guide