 Producer Gianni Nunnari was not the only person planning a film about the Battle of Thermopylae ; director Michael Mann already planned a film of the battle based on the book Gates of Fire . Nunnari discovered Frank Miller 's graphic novel 300 , which impressed him enough to acquire the film rights . 300 was jointly produced by Nunnari and Mark Canton , and Michael B. Gordon wrote the script . Director Zack Snyder was hired in June 2004 as he had attempted to make a film based on Miller 's novel before making his debut with the remake of Dawn of the Dead . Snyder then had screenwriter Kurt <unk> rewrite Gordon 's script for production and Frank Miller was retained as consultant and executive producer . 
