In George Clooney's "Good Night, and Good Luck." (weird punctuation and all), David Strathairn plays legendary journalist Edward R. Murrow during his 1950s' crusade against the communist-obsessed, witch-hunting U.S. Senator Joseph McCarthy. McCarthy, meanwhile, is played by ... himself, via the miracle of archival footage, editing and digital technology. It's not the first time a deceased figure has been plopped into a new setting, and we are positive it shall not be the last.

Perhaps this posthumous performance syndrome is Ed Wood's greatest legacy. When Bela Lugosi died during production of the 1959 anti-classic, "Plan 9 from Outer Space," director Wood used miscellaneous footage of the former Dracula (along with a very unconvincing replacement actor) to fill in the blanks. Wood's remaining undeterred in the face of his star's demise illustrated a sort of prescience on his part; the man simply didn't possess the technology to smoothly integrate Lugosi's performance with those of his still-breathing co-stars. (Imagine the results if he had!)

Carl Reiner's "Dead Men Don't Wear Plaid" (1982) starred Steve Martin in a comedic homage to classic detective film noir. The movie intercut scenes from old films like "The Killers," "The Big Sleep" and "Double Indemnity" with new black-and-white material so that Martin starred alongside screen legends Humphrey Bogart, James Cagney, Ingrid Bergman and many more. But the visual tricks were basically the same blue screen methods we've seen for decades, or new versions of the reverse-shot, stand-in techniques that Hollywood has employed since the dawn of the medium. Martin never fully steps into the old films.

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The first film to seamlessly create the illusion of actors appearing in archival footage was Woody Allen's 1983 mockumentary, "Zelig," which told the tale of a neurotic man (Allen — duh) with chameleonic powers who finds himself smack in the midst of some of the signature events of the 20th century. The movie placed Zelig alongside such figures as F. Scott Fitzgerald, William Randolph Hearst, Al Capone, Lou Gehrig, Josephine Baker and, in the film's funniest and most surreal moment, Adolf Hitler. Such visual trickery is a walk in the park for today's digital F/X folks, but 22 years ago, the result was staggering.

It would be another 11 years before CGI took posthumous performances to the next level, in "Forrest Gump." In Robert Zemeckis' 1994 film, the chocolate-box philosopher (Tom Hanks) rubs elbows — and, memorably, buttocks — with presidents JFK, Lyndon Johnson and Richard Nixon, among other real-life luminaries.

Recent years have seen an increasing number of performances from beyond the grave on the big and small screen: Oliver Reed died during the filming of 2000's "Gladiator," but digitally fulfilled his contract; Sir Laurence Olivier posthumously played the villainous Dr. Totenkopf in 2004's "Sky Captain and the World of Tomorrow"; Fran Drescher's "Nanny" character met Lucille Ball; and who can forget the creepy final performance of Nancy Marchand's head in the "Proshai, Livushka" episode from "The Sopranos"' third season?

The dead live on in other media, as well. In 1991, a Diet Coke ad had Elton John tinkling the ivories with trumpet accompaniment from Louis Armstrong at a party attended by Bogart, Cagney and Christie Brinkley (one of these things is not like the other). Madison Avenue, always a bandwagon jumper, followed up with more dead celebrities hawking stuff: Fred Astaire danced with a Dirt Devil; John Wayne shilled for Coors Light; Picasso pitched BMWs.

Meanwhile, music videos showed both Natalie Cole and Hank Williams Jr. in duets with their departed dads. In 2003, Frank Sinatra, gone since 1998, played 14 sold out shows at Radio City Music Hall. A huge, digitized Ol' Blue Eyes loomed over a live orchestra and sang the great American songbook. Hey, at least the drummer didn't have to worry about Frank threatening to punch his lights out if he was off-tempo.

Clooney claims that he used existing film of McCarthy in "Good Night, and Good Luck." because he couldn't find anyone who captured the paranoid senator's angry, sweaty neurosis just right (or maybe he thought audiences would think it was simply overacting). And he's got a point. Some historical figures are so ingrained in our collective consciousness that no thespian, regardless of talent, can ever truly make us believe in them (Philip Seymour Hoffman excepting the rule as "Capote"). No actor tackling the role of Adolf Hitler, for instance, could come close to capturing that pure personification of evil. And has there ever been an onscreen portrayal of Elvis Presley that didn't seem like an impersonation straight off of a Las Vegas stage?

But isn't the use of filmed performances from the past — even iconic fictional roles — a threat to today's working actors? How far will it go? It's one thing to use old cutting-room-floor footage of Marlon Brando as Jor-El to bring him back to the Fortress of Solitude in a cameo for next year's "Superman Returns," but what if someone wants to create an entirely digital Brando to star in "The Wild One Goes Wild (Miami Beach)" or "The Godfather Part IV"? And what happens when the digitally morphed actors want bigger billing?

The posthumous performance syndrome is a Pandora's Box that Hollywood can't close, and no doubt some struggling actors are worrying that the day is fast approaching when they're going to have to compete not only with Cameron Diaz and Orlando Bloom, but Marilyn Monroe and Cary Grant, as well. They'd best not quit their day jobs.

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