Following the news that Natalie Portman will be playing the former first lady in Jackie, Laura Morgan celebrates the good, the bad and the ugly of celebrity casting.

There are all sorts of pitfalls to be avoided when casting an actor to play a real-life celebrity. Naturally we all project our own versions of famous folk on to the little we actually know about them, concocting detailed personalities who presumably bear little resemblance, except physically, to the real thing. But most of us are grown-up enough to accept that Alfred Hitchcock might have been nastier, Virginia Woolf ditzier, Fred West wittier, than we imagined. And even if they weren’t, we’d rather film-makers employ poetic licence if it means a better film.

But I am much less forgiving of the sort of terrible series of decisions which leads to casting, for example, Naomi Watts as Princess Diana. There are some simple rules which ought to be followed under these circumstances, and I will share them with you now in the hope that you are in charge of casting the next big celebrity biopic (I just know you’ll do a great job!).

• Don’t cast someone infamous to play someone famous. There’s no point having Lindsay Lohan play Elizabeth Taylor when Lindsay Lohan is uniquely, ineffably and always Lindsay Lohan. Liz and Dick, like every Lindsay Lohan vehicle, is a Lindsay Lohan vehicle.
• Don’t cast someone we know and love as someone we are meant to hate. The casting in FX’s recent The People Vs OJ Simpson was nearly all brilliant (of which more later), but Cuba Gooding Jr is all wrong as OJ, not because he didn’t give a great performance (although, as an aside, OJ must be the hardest part to play because how do you play a probable murderer if you don’t know for sure whether you did it in real life?), but because he looks like a teddy bear, and however hard he tried to be intimidating and filled with a vengeful rage, he was still Cuba Gooding Jr and none of us was even a little bit scared of him.

• You must always cast someone at least as good-looking as the person they’re portraying. Anything else is just impolite. Sam Riley as Ian Curtis; Salma Hayek as Frida Kahlo; Aaron Taylor Johnson as John Lennon – these are all respectful, flattering choices. This, of course, is why it’s impossible to make a good Elizabeth Taylor biopic, and why it should be impossible to make a good Marilyn Monroe biopic, except that Michelle Williams in My Week With Marilyn just about gets away with it, because she is silly and sweet and sexy in just the right way, without really looking anything at all like Marilyn.
• You have to be careful not to slip into doing impressions, which also means being careful about whom you choose to make the subject of your movie. Michael Sheen was perfectly fine as David Frost, Brian Clough and Tony Blair. As Kenneth Williams he gave a spot-on impersonation which couldn’t help but slip into parody from time to time, largely because Williams was an expert in self-parody. In general, the easier it is to do an impression of a person, the less good an idea it is to have someone play them straight. This is one of several reasons why there will never be successful biopics of Tom Waits, Jimmy Savile or Miss Piggy.
• If in doubt, have lesser-known actors play your celebrities. The BBC’s snooker drama The Rack Pack premiered on the iPlayer earlier this year and was shown on BBC2 last weekend to coincide with the World Championship finals in Sheffield (and is therefore back on the iPlayer, in case you missed it). Kevin Bishop as Barry Hearn, James Bailey as Jimmy White and Russ Bain as Cliff Thorburn all deserve special mention, but the crowning glory of the piece is Will Merrick, looking more like Steve Davis than Steve Davis has ever done:

• Even better, have A-listers playing your secondary characters. This was the note of genius in the casting of The People Vs OJ Simpson, which featured actors (David Schwimmer, John Travolta, Nathan Lane) who were themselves huge at the time of the original trial in 1995, in over-the-top, hammy performances which should have been terrible, but were in fact a perfect way to depict what was, after all, an over-the-top, hammy moment in history. Everyone (apart from Cuba) looks enough like the people they play to make it fun to compare them to the real thing, but essentially, and entirely deliberately, they are also playing themselves.

Sometimes two famous faces resemble each other so closely that it would be plain churlish not to cast one as the other. Which brings us back to where we came in, because we have already seen a disconcertingly perfect (visually: she struggled with the accent) Jackie O from Katie Holmes, who played her in the 2011 TV miniseries The Kennedys, and will reprise the role in the upcoming The Kennedys: After Camelot (I know, me too). This is what you have to live up to, Natalie:

Some of the greatest fantasy casting choices remain unrealised. I asked fellow MostlyFilm writers over on our forum to nominate their picks of actor and actee, and am therefore pleased to be able to tell you that once they put us in charge, you will be seeing biopics featuring, among others, Reese Witherspoon as Madeline Kahn, Kelsey Grammer as Bob Hope, Vic Reeves as Eric Morecambe and Benedict Cumberbatch as Butthead.

If that sounds like a script you want to write, let us know!