According to Film School Rejects plans could be afoot to create a sequel to 300. What's next? Watchmen 2: They're still Watching?
Despite the fact that there's only one 300 graphic novel, the flick did make a galley ship of money, and producer Mark Canton is said to be keen for Frank Miller to write a follow-up, and for Zack Snyder to direct it.
Whether either will want to return to the Spartans probably depends on the successes of their next comic-book flicks, with Miller's The Spirit and a little film called Watchmen on the horizon.
Source: (Film School Rejects)