Navigating the Percy Jackson timeline can initially feel a bit like trying to map the Labyrinth itself, but once you get the lay of the land, it’s a fantastically interconnected journey. The core spine is, of course, Rick Riordan’s original 'Percy Jackson and the Olympians' series. You’ll want to start with 'The Lightning Thief' and move through 'The Sea of Monsters', 'The Titan’s Curse', 'The Battle of the Labyrinth', and conclude with 'The Last Olympian'. This five-book arc tells Percy’s foundational story, from discovering he’s a demigod to the epic showdown with the Titan Lord Kronos.
Once you’ve wrapped up Percy’s first major war, the next logical step is the sequel series, 'The Heroes of Olympus'. This picks up a few months after 'The Last Olympian' and expands the world to include Roman demigods. Read them in order: 'The Lost Hero', 'The Son of Neptune', 'The Mark of Athena', 'The House of Hades', and 'The Blood of Olympus'. This series introduces a whole new cast of characters like Jason, Piper, and Leo while deepening the roles of Percy, Annabeth, and others, culminating in the threat of Gaea.
From there, you can move into 'The Trials of Apollo', which directly follows the events of the previous series. It begins with 'The Hidden Oracle', where a now-mortal Apollo is cast down to Earth, and continues through 'The Dark Prophecy', 'The Burning Maze', 'The Tyrant’s Tomb', and ends with 'The Tower of Nero'. While Percy takes more of a supporting role here, this series ties up numerous lingering threads from the entire mythic universe Riordan built. For the most cohesive experience, I’d recommend reading these three main series in their publication order as listed.
There are also supplemental stories that slot into the timeline. The 'Magnus Chase and the Gods of Asgard' trilogy (which begins with 'The Sword of Summer') runs concurrently with 'The Trials of Apollo', and the 'Kane Chronicles' (starting with 'The Red Pyramid') exists in a parallel, Egyptian-magic-focused universe with a couple of fun crossover stories. For completists, short story collections like 'The Demigod Files' and 'The Demigod Diaries' fit between the novels, offering extra adventures. It’s a sprawling timeline, but starting with Percy’s own five books is the perfect gateway into this endlessly entertaining modern mythology.