Percy Jackson & the Olympians is a series of five fantasy novels written by American author Rick Riordan, and the first book series in the Camp Half-Blood Chronicles. The novels are set in a world with the Greek gods in the 21st century, and follows the protagonist Percy Jackson, a young demigod who must prevent the Titans, led by Kronos (Cronus), from destroying the world.

The first three books were published in the United States by Miramax Books before it was folded into Hyperion Books, which published the following books. All the books were published in the United Kingdom by Penguin Books. Five supplementary books, along with graphic novel versions of each book, have also been released. As of January 2022, the books have sold more than 180 million copies worldwide, making it one of the best-selling book series of all time. Two sequel series, The Heroes of Olympus and The Trials of Apollo, follow.

The first book was adapted into a film titled Percy Jackson & the Olympians: The Lightning Thief in 2010, which was commercially successful, but received mixed reviews from critics and the audience as it has very few similarities to the book. An adaptation of the second book, titled Percy Jackson: Sea of Monsters, was released in 2013, also to mixed reviews. A TV series based on the novels is currently in production for Disney+.