Typecasting can be the death of many a good actor's career, as Christopher Eccleston is no doubt aware.
By Neil Smith
BBC News entertainment reporter
Why else would the 41-year-old Mancunian turn his back on Doctor Who just one episode into its new series?
Eccleston has decided to leave Dr Who after just one series
But Eccleston may find it harder than he imagines to cast off the Time Lord mantle.
For the annals of film and TV are littered with actors who will forever be associated with one iconic role.
Take Sean Connery, who shot to fame as James Bond only to find audiences unwilling to accept him as anything else.
"I have always hated that damn James Bond," he once said. "I'd like to kill him."
But that did not stop him from returning to the part on two occasions: first in 1971's Diamonds Are Forever, and again, belatedly, in 1983's Never Say Never Again.
In recent years Connery appears to have moved on, winning an Oscar for The Untouchables and reinventing himself as a gruff, grey-bearded character actor.
However, he acknowledges he will never completely discard Ian Fleming's suave superspy, saying: "It's with me till I go in the box."
The late Christopher Reeve suffered a similar fate after playing the Man of Steel in 1978's Superman.
Christopher Reeve played the Man of Steel in four films
The Julliard-trained actor became a star overnight but - like Connery before him - could not make a similar impression in any other role.
"I asked Sean on how to avoid being typecast," he once revealed. "He said, 'First you have to be good enough that they ask you to play it again and again'."
Reeve was certainly good enough - perhaps too good. Though he tried to shake his heroic image - notably by playing a murderer in the 1980 thriller Deathtrap - he was unable to, as he put it, "escape the cape".
Other actors have resorted to drastic measures to reinvent themselves on screen.
Frustrated with her goody-two-shoes persona, Julie Andrews stunned moviegoers by baring her breasts in 1981 comedy S.O.B.
"I don't want to be thought of as wholesome," she said at the time. "Does Mary Poppins have an orgasm? Does she go to the bathroom? I assure you she does."
Merchant Ivory regular Helena Bonham Carter was equally daring in her attempts to wriggle out of her period drama corset.
Who's that chimp? Helena Bonham Carter in Planet of the Apes
"I hate this image of me as a prim Edwardian," she once said. "I want to shock everyone."
That she did by playing a chain-smoking drug addict in Fight Club and, more bizarrely, a monkey in Planet of the Apes.
Her boldness was echoed recently by Bend It Like Beckham actress Keira Knightley, who deliberately pursued the role of a troubled alcoholic in psychological thriller The Jacket.
"As a British actor in Hollywood you get typecast very fast," she said in January.
"I don't want to play the same character for my entire career. That would be supremely boring."
Try as they might, however, some actors will forever be linked to one career-defining role.
None more than Sir Alec Guinness, whose legendary triumphs on stage and screen were completely overshadowed by his involvement in Star Wars.
"I shrivel up every time someone mentions it," he once said.
Indeed, on one occasion he brought a small boy to tears by requesting he never see Star Wars again.
Sir Alec regretted playing Obi-Wan Kenobi in Star Wars
In an interview published a year before his death, the actor revealed how he had persuaded director George Lucas to kill off Obi-Wan Kenobi by saying his character would be more effective as a ghost.
"What I didn't tell him was I just couldn't go on speaking those bloody awful, banal lines. I'd had enough of the mumbo jumbo."
There are advantages to being typecast, however, as horror veteran Christopher Lee discovered after playing Dracula for the first time in 1958.
"I do not regret anything," he said.
Playing the Count gave him "a name, a fan club and a second-hand car, for all of which I was grateful".