Carey Mulligan playing with fire in classic role

As casting announcements go, it was fascinating. Late last year, Baz Luhrmann picked the British actress Carey Mulligan to play the 1920s socialite Daisy Buchanan in his forthcoming adaptation of The Great Gatsby.

It had been an arduous audition process: Mulligan was said to have been up against the likes of Keira Knightley, Scarlett Johansson and Natalie Portman. So when the star of An Education took the call from Luhrmann - which began "Hello, Daisy Buchanan" - Mulligan forgot her surroundings (a rather public red carpet at a New York fashion awards) and burst into tears. A few weeks ago, she told the BBC that by her bed she had a copy of The Great Gatsby "that I'm obsessively reading".

But Mulligan would do well not to pay too close attention to this classic of American literature by F Scott Fitzgerald - not least because it's generally regarded as unfilmable. The 1974 version completely miscast Robert Redford in the role of the enigmatic roughneck Jay Gatsby: the part calls for an element of mystery, intrigue and probably an unknown actor - not the bluster of the Sundance Kid.

Lurhmann hopes to start filming later this year, but in casting so many big names (Leonardo DiCaprio is to take the title role) he may be falling into the same directorial traps as his predecessors.

Still, if anyone has the ability to take on such well-loved literary characters - never an easy task - then it's Luhrmann. After all, literature's foremost romantic hero must be Shakespeare's Romeo, and the Australian director fashioned a wonderfully modern take on Romeo and Juliet in 1996. It worked because Luhrmann (and DiCaprio in the lead role) seemed to understand the literary qualities of the source material. Hence, the setting may have been unfamiliar - warring business empires rather than feuding feudal clans - but the language remained unchanged.

Romeo + Juliet is notable because Hollywood is slowly becoming less keen on the timeless characters imprinted upon our literary culture. Instead, the studios are generally turning to more modern books, such as Cormac McCarthy's No Country for Old Men, Vikas Swarup's Q&A (filmed as Slumdog Millionaire) and Sylvia Nasar's A Beautiful Mind, all of which have inspired Oscar-winning adaptations over the past decade. There's a sense that it's modern stories that have become important, rather than old characters.

Perhaps the classics are now too well-worn. Keira Knightley might have been a pleasing enough Elizabeth Bennet in Joe Wright's 2005 version of Pride and Prejudice. But we all know how that one ends, and the film was constantly compared with the impeccable BBC serial 10 years earlier. From the moment that hit the television screens, Colin Firth was Darcy.

Current depictions of classic characters very much reflect our times and tastes. Guy Ritchie's Sherlock Holmes retained the Victorian setting of Sir Arthur Conan Doyle's classic, but ramped up the action and the odd-couple double act between Holmes (Robert Downey Jr) and Watson (Jude Law). It was, rather surprisingly, a success and a sequel is planned. Significantly, though, it wasn't an adaptation of an original Conan Doyle story but a vehicle for Downey. Announcing his part in the film, he called Holmes "quirky and nuts… just such a weirdo. It could be a description of me on some days".

Another famous character to hit our screens again last year was Lewis Carroll's Alice. Tim Burton's Alice in Wonderland was hardly a straight adaptation, though. In the book, the heroine is six years old, yet in the film she was 19, played by Mia Wasikowska.

Admittedly, the screenplay made it quite clear that Alice was returning to Wonderland for the first time since she had been a little girl. But the childish wisdom that gives the book its emotional depth was lost. As it turned out, Tim Burton's version was just another slightly disappointing addition to a string of Carroll adaptations from across the decades.

And 2010 ended with a woeful take on Jonathan Swift's masterful creation Lemuel Gulliver. Jack Black rode roughshod over this complex character. At least when Ben Barnes played a cinematic version of Dorian Gray in 2009, he imbued the hero of Oscar Wilde's Faustian fable with a little humility and guile.

Nevertheless, Barnes was not quite as good as Hurd Hatfield in Albert Lewin's 1945 version of The Picture of Dorian Gray. And most of the great cinematic character studies are to be found in film's distant history. Gregory Peck's take on Atticus Finch in the 1962 adaptation of Harper Lee's 1960 novel To Kill a Mockingbird was his career high, surely because Peck completely understood his character.

"The Southern town of Maycomb, Alabama, reminds me of the California town I grew up in," he wrote in the foreword to a later edition of what is now recognised as a landmark in American literature. "The characters of the novel are like people I knew as a boy. I think perhaps the great appeal of the novel is that it reminds readers everywhere of a person or a town they have known."

The performance won Peck a Best Actor Oscar in 1962, but it was To Kill a Mockingbird's misfortune to be produced in the same year as David Lean's all-conquering Lawrence of Arabia.

Lean was the master of shaping great movies from the classics of literature. This giant of filmmaking built his career on the backs of two wonderful Charles Dickens adaptations: Great Expectations in 1946 and Oliver Twist in 1948. The latter has since been tackled by everyone from Carol Reed to Roman Polanski, but nobody has matched Alec Guinness's Fagin for sheer grotesqueness.

Lean's films were generous to fans of the source texts without following them slavishly, an approach he used again in 1965 with Boris Pasternak's epic romance Doctor Zhivago. Omar Sharif was utterly convincing as the selfless doctor, and again there was an emotional investment in the role: Sharif loved the book.

Of course, it's not a given that classic characters make for classic films. One wonders why Stanley Kubrick even bothered rendering Vladimir Nabokov's controversial masterpiece Lolita to celluloid in 1962 (even though Nabokov was involved in its production).

Censorship laws in the US were such that - rightly, you might argue, considering its content - the film was patchy and uneven. Worse still, the 1997 Adrian Lyne version appeared to ignore the crucial comic element to the text. But neither was as toe-curlingly, embarrassingly bad as Roland Joffé's 1995 adaptation of Nathaniel Hawthorne's The Scarlet Letter.

The protagonist of the 1850 American masterpiece, Hester Prynne, is one of the great heroines of American literature. Demi Moore, however, simply played her as a steamy marriage-wrecker.

Perhaps Moore's slightly tragic performance contained a lesson: to fashion a satisfying adaptation, you need a star who understands and respects his or her character's importance as an enduring literary figure. But you also need a director who can make that character relevant in 2011 while at the same time preserving the very elements that make these stories and people timeless.

Can Baz Lurhmann, Carey Mulligan and Leonardo DiCaprio pull off that delicate balancing act? We shall see.