The 2006 film "300" is based on a graphic novel written by comic book creator Frank Miller.
Miller's "300" was originally a five-issue limited comic-book series published by Dark Horse Comics in 1998. He wrote and illustrated the series, while Lynn Varley provided its painted colors. The story is a highly stylized fictional retelling of the Battle of Thermopylae, told largely from the perspective of King Leonidas of Sparta and his warriors.
The comic was inspired in part by the 1962 film "The 300 Spartans," which Miller watched as a child. Zack Snyder directed the 2006 movie adaptation and co-wrote its screenplay with Kurt Johnstad and Michael B. Gordon, but Snyder was not the creator of the original graphic novel. The film expands and dramatizes Miller's imagery, framing, dialogue, and visual approach.
History and movie storytelling should not be treated as identical here. The historical battle took place in 480 BCE during the Greco-Persian Wars, but the graphic novel and film use fantasy elements, exaggerated violence, and invented scenes. Miller is also known for "Sin City," "Ronin," "The Dark Knight Returns," and his influential work on "Daredevil."