According to the LA Daily News, the filmmakers of Watchmen are looking to cast look-alikes of people-of-notoriety to appear in the film:

A challenging casting task involving look-alikes is under way for Warner Bros.' Watchmen adaptation of Alan Moore's 1980s graphic novel set in an alternative universe's United States. Names include Richard Nixon, Henry Kissinger, H.R. Haldeman, Ted Koppel, John McLaughlin, Annie Liebowitz, John Lennon and Yoko Ono, Fidel Castro, Albert Einstein, Norman Rockwell, JFK and Jackie Kennedy, Andy Warhol, Mao Tze Tung and Larry King. That's going to be quite a movie.
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The Zack Snyder directed film will arrive in theatres in 2009.