Perhaps the most surprising name to pop up on this year’s Oscar shortlists is – drumroll – Katharine Hepburn. Only this time the actress, who died in 2003 after going 4-for-4 in Best Actress nominations, is not being suggested as a potential nominee, but as a character.

In “The Aviator” the silver-screen legend is portrayed by one of our own era’s best actresses, Australian Cate Blanchett. Some will declare Ms. Blanchett’s portrayal sacrilege – which is silly, since the only person whose reputation is at risk is Ms. Blanchett’s own. (Hepburn impersonation has long been a cottage industry in venues like “Saturday Night Live” and has done little to affect her regal aura.) The more worrying issue is what happens when actors begin playing themselves instead of real people.

Ms. Blanchett is not the only actor taking a bite out of a movie icon this season. In “The Aviator” alone we have, besides Ms. Blanchett, Kate Beckinsale as Ava Gardner, Gwen Stefani as Jean Harlow, and Jude Law as Errol Flynn. Also opening today is “Beyond the Sea,” a vehicle serving Kevin Spacey’s Bobby Darin fixation (it features Kate Bosworth as Sandra Dee). Earlier this month, HBO viewers saw a slew of stars play other stars in “The Life and Death of Peter Sellers.” Such impersonations have been common, if occasional, on television. Their leap to the big screen tells us less about actors and their proclivities, though, than our own desires. If the success of “Behind the Music,” and the avalanche of tawdry television movies detailing the drama-wracked sets of “The Brady Bunch” and “Three’s Company” are any indication, audiences are growing less interested in real-life stories and more interested in star stories.

Historically, few actors have portrayed brighter stars with any degree of success. A few exceptions that leap to mind are Robert Downey Jr. as Charlie Chaplin in “Chaplin” and Judy Davis as Judy Garland in the 2001 television movie, “Life with Judy Garland: Me and My Shadows,” that aired on ABC. For every Jessica Lange (Frances Farmer in 1982’s “Frances”),however, there are two Jennifer Love Hewitts (in the abysmal 2000 television biopic of Audrey Hepburn).

The ultimate cautionary tale in this regard may be Faye Dunaway, whose uncanny, over-the-top impersonation of Joan Crawford in “Mommie Dearest” derailed her once luminous career. The problem wasn’t that Ms. Dunaway was unconvincing. It was the opposite: Ms. Dunaway, a diva herself, became movie-queen-in-decline Crawford, and the two actresses are now irrevocably linked in B-movie camp hysteria.

Picasso called art “the lie that tells the truth.” But if a performance is in part based on previous movie performances, isn’t it more like a lie that tells a lie – a simulacrum at best?

The curious thing about movies like “The Aviator” or “The Life and Death of Peter Sellers” is that they resemble more than anything magazine articles from star-struck magazines like Vanity Fair or Star. (“The Aviator” was even the subject of an expansive photo spread in Vanity Fair a few months ago.) Like a hungry shark, Hollywood is learning from its parasites to cannibalize itself: If audiences are more interested in movie-star personas than real people, then give them what they want.

But you have to wonder what movies will arrive after we exhaust the classic actors, once Jim Carrey has taken on Cary Grant and Colin Farrell has won the Oscar for portraying Peter Lorre; when our nostalgia speeds up to the point that it converges with our celebrity worship; that is, when we long for the golden age of last year’s Star magazine. A movie about Nicole Kidman starring Kate Winslet? A biopic of Julia Roberts starring Julia Roberts?

The frightening thing – which you’ll know if you hit the movie theaters last week to catch the lazy movie-star commercial “Ocean’s 12” – is that we’re already halfway there. At one point in the convoluted plot, Ms. Roberts’s character, art curator Tess Ocean, briefly impersonates …famous movie star Julia Roberts. In this coy wink at his audience’s own starstruckness, director Steven Soderbergh picks up the heady gauntlet thrown down by screenwriter Charlie Kaufman, who, in 1999’s “Being John Malkovich,” implied that everybody wants to be inside the head of a movie star.

Even, it turns out, movie stars themselves.