Richard Russell Riordan Jr. ( RY-ər-dən; born June 5, 1964) is an American author, best known for his Camp Half-Blood Chronicles, which includes the Percy Jackson & the Olympians series, The Heroes of Olympus series, The Trials of Apollo series, and The Nico di Angelo Adventures series. Riordan's books have been translated into 42 languages and sold more than 30 million copies in the United States. Riordan's first full-length novel was Big Red Tequila, which became the first book in the Tres Navarre series. His breakthrough was The Lightning Thief (2005), the first novel in the five-volume Percy Jackson & the Olympians series, which placed a group of modern-day adolescents in a Greco-Roman mythological setting. Since then, Riordan has written The Heroes of Olympus, a sequel to the Percy Jackson series; The Kane Chronicles, a trilogy of similar premise focusing on Egyptian mythology; and Magnus Chase and the Gods of Asgard, a trilogy of similar premise focusing on Norse mythology. Riordan also helped Scholastic Press develop The 39 Clues series and its spinoffs, and penned its first book, The Maze of Bones. In 2021, he published Daughter of the Deep. His fourth spin-off series set in the Percy Jackson universe, The Nico di Angelo Adventures, began on May 2, 2023, with the release of The Sun and the Star, co-written with author Mark Oshiro. Originally planned as a standalone novel, positive critical reception lead to the publishing of a sequel The Court of the Dead in 2025. 20th Century Fox adapted the first two books of his Percy Jackson series as part of a film series, which Riordan was not involved with. Riordan currently serves as a co-creator and an executive producer on the television series adaption of his Percy Jackson series that was released on Disney+ in 2023 and for which he won two Emmy Awards. Riordan's books have also spawned other related media, such as graphic novels and short story collections.