At the end of the Questions/Answers session following the press preview of Watchmen, a journalist asked if the actors had a sequel clause.
Zack Snyder (300), the director, said he didn't know if they did, but said there could not be a sequel or a prequel to Watchmen. He continued that if there was, he would not be a part of it.
Watchmen is the adaptation of Alan Moore and Dave Gibbons' 1986 comic book limited series Watchmen and will be hit theaters in March 2009.
The story is set in an alternate 1985 where superheroes exist, Richard Nixon is still president, and tensions between the United States and the Soviet Union are at an all-time high. The vigilante Rorschach is investigating the murder of a former hero, the Comedian, and uncovers a plot to discredit and murder various heroes. Rorschach discovers a far wider-ranging conspiracy involving his colleagues' past which could completely change the course of history.