The Heroes of Olympus is a pentalogy of fantasy-adventure novels written by American author Rick Riordan. The novels detail a conflict between Greek demigods, Roman demigods, and Gaea. In the fourth book of the series, there is also a fight against Tartarus, which, in Greek mythology, was the darkest and deepest point of the Underworld.

Richard Russell Riordan Jr. is an American author, best known for writing the Percy Jackson & the Olympians series. Riordan's books have been translated into forty-two languages and sold more than thirty million copies in the United States. 20th Century Fox adapted the first two books of his Percy Jackson series as part of a series of films in which Riordan was not involved. Riordan currently serves as a co-creator and executive producer on the television series adaption of the book series that was released on Disney+ in 2023. Riordan's books have also spawned other related media, such as graphic novels and short story collections.