Wyatt Earp is Tombstone's main character, but Doc Holliday is its hero – at least to me. Kurt Russell's Earp is tall, straight-backed and broad-shouldered. He has tanned skin and a personality as imposing as his physique. Val Kilmer's Holliday is smaller and unmistakably sickly. He has a vampiric pallor and constantly coughs, stumbles and sweats. He's dying of tuberculosis, but he's still the fastest gun in the west.

Like Doc Holliday, I am diminished and disabled by long-term illness. Like him, I spend much of my time suffering in bed, recovering from brief exertions. But my brief exertions don't include winning the gunfight at the OK Corral or 12 consecutive pots at poker. When people hear that the movie character I would most like to be is from Tombstone, they assume I mean Wyatt Earp. I can never understand why.

Wyatt Earp is good in a gunfight – he's brave and generally hits what he aims at – but he's not a gunfighter in the classic sense. He's no quick-draw specialist. In contrast, the outlaw Johnny Ringo (Michael Biehn) is a legitimate gunslinger. Ringo engineers fights he knows he will win, like a boxer hand-picking his opponents. This is why he challenges Earp to a one-on-one shoot-out. And it is why, learning of the challenge, Doc Holliday staggers from his sickbed to take Earp's place.

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For me, what follows is one of the most inspiring sights in cinema: the disabled supporting character fighting through his physical limitations to easily defeat an enemy who has the film's great able-bodied hero completely outclassed. When Ringo thinks he sees Earp approaching, he is thrilled and eager to fight. When he recognises instead the pallid, infirm figure of Doc Holliday, he is suddenly terrified and stammers that their previous disagreements don't amount to a real quarrel. "I was just foolin' about," says Ringo.

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"I wasn't," says Holliday, and his eyes announce that the reckoning has arrived. It's the coolest a chronically ill character has ever looked on screen. By this point, Wyatt Earp would already have been dead.

Growing up, I often fantasised about being one of the heroes of the old west played by Clint Eastwood or John Wayne, but I eventually realised that, if I became one, I'd have to give up my favourite pleasures. Rooster Cogburn and The Man With No Name are not noted for their sensitivity to the arts.

But if I became Kilmer's Doc Holliday, I could be a legendary gunslinger and still be a bookworm. Holliday excels at the rough business of gambling and gunfighting, more so than any of the rough men around him, and yet he is educated and elegant. He speaks Latin, quotes Coleridge and plays Chopin on a saloon piano, sending his adoring girlfriend (Joanna Pacula) into erotic reveries.

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And this is another reason I want to be him: women want to be with him. It is hard to feel attractive when you are chronically ill. Kilmer's Doc Holliday makes chronic illness look good. He's a sexy, Keats-esque consumptive. I dream of being a sexy, Keats-esque consumptive. As a long-term invalid, it's the strongest look I can reasonably hope to achieve.

Many seriously ill movie characters are inspirational, but the inspiring message they usually send to seriously ill viewers is that we can learn to make peace with our awful situations or perhaps overcome them enough to get a degree or fight a court case. As wish-fulfilment goes, that's pretty tame. Doc Holliday proves you can be chronically ill and still be an action hero.

• Why I'd like to be … Hugo Weaving in The Matrix

• Why I'd like to be … Michael J Fox in Back to the Future

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