1. *Percy Jackson & the Lightning Thief* (2005)
2. *Percy Jackson & the Sea of Monsters* (2006)
3. *Percy Jackson & the Titan's Curse* (2007)
4. *Percy Jackson & the Battle of the Labyrinth* (2008)
5. *Percy Jackson & the Last Olympian* (2009)
However, the Percy Jackson story continues in other series and books:
* The Heroes of Olympus (5 books): This series features Percy Jackson and other characters from the first series.
* The Trials of Apollo (5 books): This series features Apollo as a mortal, and Percy makes an appearance in one of the books.
* The Kane Chronicles (3 books): This series takes place in the same universe but focuses on different characters and Egyptian mythology.
* Magnus Chase and the Gods of Asgard (3 books): This series takes place in the same universe but focuses on Norse mythology and different characters.
* The Demigod Diaries: A collection of short stories and novellas featuring characters from the *Percy Jackson & the Olympians* and *The Heroes of Olympus* series.
* Percy Jackson & the Olympians: The Graphic Novel Series: Graphic novel adaptations of the original Percy Jackson series.
So, while there are five main Percy Jackson books in the *Percy Jackson & the Olympians* series, the story continues in other books and series, expanding the world of Rick Riordan's mythology.