The Lightning Thief belongs to the Percy Jackson and the Olympians Series. In this series, there are five books. In the order that they were published, they are, The Lightning Thief, The Sea of Monsters, The Titan's Curse, The Battle of the Labyrinth, and The Last Olympian. The Heroes of Olympus is the series that comes after Percy Jackson and the Olympians. The books of The Heroes of Olympus, in order, are The Lost Hero, The Son of Neptune, The Mark of Athena, The House of Hades and The Blood of Olympus. The final series that includes Percy, so far , is The Trials of Apollo. The books are, The Hidden Oracle, The Dark Prophecy, and The Burning Maze. Along with writing Greek Mythology, Riordan has written about Norse mythology, in Magnus Chase and the Gods of Asgard, and Egyptian mythology in The Kane Chronicles. Riordan is also one of the 39 clues writers.