Such movies like "Clash of the Titans" and the new one coming up, "Percy Jackson & the Olympians:
The Lightning Thief" should be categorized as historical fantasies. The plot is based on a thread of historical folklore and in the case of "Lightning Thief," is brought forward to our present time. If not for the sliver of folklore attached to the story, this book and movie would be categorized as "urban fantasy" which is a fictional fantasy pulled into contemporary urban settings.
Historical fiction hasn't been doing very well in print. Add some romance to the historical story and market the story as a romance instead of pushing the historical slant and you've got the sales coming in. If you don't have enough romance in the story, then make sure there is enough adventure.
"Percy Jackson & the Olympians: The Lightning Thief" is coming to the screen this week, February 12th. This movie is based on a book by Rick Riordan. The synopsis reads the story is about a teenager who discovers he's the descendant of a Greek god and sets out on an adventure to settle an on-going battle between the gods. Sounds like the ultimate fantasy to me.
"Clash of the Titans" is coming out March 26th in the regular screens, but they are also coming out with a 3D version April 2nd. Even though I love historical fantasies, I will personally stay out of the 3D version of "Clash of the Titans" because I HATE scorpions. What's worse than a scorpion? HUGE scorpions coming at you in 3D!!