Preview of essay
There are many references to the Masters in 300, and some (anachronistically?) refer to Christian themes. Here are some of my observations.
There is the reference to Goya's "The Third of May" when the brave Spaniard stands with his arms outstretched before the shooting squad. Leonidas does this before the arrows of the Persians - and we see this from behind.
There is the reference to St. Sebastian's arrow-pierced body upon seeing Leonidas fallen down after the barrage of the Persians' assault.
There are the charging horses of Delacroix, which the Persians (Arabs in Delacroix's paintings) ride.
Others have mentioned the Greek vases and their depictions of silhouetted soldiers. This makes more sense than what appear to be martial arts in the film (although the director did use martial artists to help choreograph his piece).
And there is the tradition of working with fully completed cartoons (mock drawings) before the final painting is attempted. This is pretty much what the director Zach Snyder did, quite faithfully using the already published Frank Miller's cartoon book (called a graphic novel these days) ) by the same name.
There is of course the ultimate image of all, the golden calf (or calves in this case) which adorn Xerxes' throne.
There are many more elements, including some beautiful sea imagery, which I think could have come from Turner, and more subtle Christian imagery.
Snyder did say he spent a long time looking at paintings.
The other phenomenal thing about the movie of course is the computerized imagery, which looks somewhat real rather than super real as would straight photography. I think paintings do this also, where the environment is not faithfully recorded as would be through a camera lens. Also, this computer generated imagery is an evolution of traditional art, at its most sublime, doing the same art but in modern times.