Pressed to name the actors, the entertainers, who have given me most pleasure, spoken most powerfully to me about the joys and tribulations of the human condition, I would top my list with comedians: Charlie Chaplin, Buster Keaton, the Marx Brothers, Lucille Ball, Peter Sellers, Jacques Tati, Woody Allen, Dad’s Army, the Monty Python gang, the folks from Fawlty Towers, the Seinfeld troupe, Larry David, Garry Shandling as Larry Sanders. We all have our favourites. Is there a higher calling in this life than the divine gift of inspiring laughter?

There is one group of people who don’t seem to feel that way: comedians themselves. Of course, we know they have a constitutional disposition towards being a tormented bunch of misanthropes. Which is pretty funny. What’s not so funny is that so many of them feel that to be taken seriously, they have to prove themselves as dramatic actors. That is a step two of Britain’s best-known comedians of recent years have now taken, on American television. There is Hugh Laurie in House, playing the limping, Vicodin-popping, snarling but somehow lovable diagnostic genius Dr Gregory House; and now, Eddie Izzard in The Riches.

It is too early to tell just how successful Izzard’s latest transformation from comedian to dramatic actor will be. Laurie, though, has made the change much more successfully than he ever expected, or, if truth be told, probably ever wanted. House is such a big hit in America (second only to American Idol in the ratings) that Laurie is probably locked into a five-year run. That means nine miserable months of the year away from his family, shooting in LA.

“I have had some very black days on this show,” he admitted recently. “But a lot of that has to do with finding the situation overwhelming. There are days I feel exposed, lonely and vulnerable.” Not at all funny.

It’s not just television. At the moment, cinema screens are overflowing with brilliant comedians who seem to feel they aren’t worthy unless they show us their sad-clown face: Robin Williams, Jim Carrey, Eddie Murphy, Steve Martin, Bill Murray and, most recently, Adam Sandler. They have all pitched their tent in the drama camp, apparently ashamed of the astonishing comedic gifts that have given us so much pleasure and made them so successful and rich.

Murray’s deadpan comedy was built around the deep well of melancholy in his hangdog face. Even so, he has spent decades trying to be taken seriously as a straight actor. His 1984 adaptation of W Somerset Maugham’s The Razor’s Edge, which he co-wrote and starred in, was a box-office disaster. He later told me it took him years to deal with the disappointment: “People were saying, ‘If this guy ever tries to do anything that’s not a comedy again, he should be arrested.’ ” He spent most of the next 20 years making comedies, with less and less enthusiasm. Luckily, his dramatic talents were rediscovered by Sofia Coppola in Lost in Translation, in which he played a lonely actor making a commercial in Japan. The role won him an Oscar nomination for best actor and the respect he felt he needed. I respected him already. Williams seems desperate to make us forget he is the most inspired stand-up comedian of his generation. He has made nasty films such as One Hour Photo, in which he played a photo-development clerk-turned-psycho-stalker; Insomnia, as a murderer; and The Night Listener, in which he was a late-night radio DJ — roles that could have been played just as well by someone else. “I can get the laughs doing stand-up,” Williams explained, “but then there’s the desire to explore the deepest, most painful stuff.” I thought exploring the deepest, most painful stuff was what made him so funny.

Also affected by the serious plague is Carrey, who just a few years ago was effortlessly making upwards of $20m a movie as America’s most dangerously zany comedian. He hinted at it in The Cable Guy, a comedy, but a deliciously misanthropic and cruel one. He followed that with effective dramatic performances in The Truman Show and Eternal Sunshine of the Spotless Mind. But he, too, evidently felt the need to explore the dark side, hence his most recent film, The Number 23, in which he plays a dog-catcher who becomes obsessed with a novel he believes has been written about him.

Carrey tried to take his audience on a journey they were unwilling to make, however. The film was a box-office disappointment and earned him a critical savaging. “Alas, this great comic talent seems to think he’s fronting a serious film,” wrote a New York Times reviewer, “an assignment for which he has reined in his body, trading his ductile physicality and natural grace for moody stares and anguished postures.” Bizarrely, the film’s director, Joel Schumacher, said Carrey wanted to play such a disturbing character because he has never been happier in his personal life. “He was afraid [in the past] that if he went to those dark places, his life would be misery the whole time he was making the movie. But now, life is good for Jim.” Would it be churlish of me to wish a dose of misery upon Carrey? Perhaps they came from an unhappy place, but give me Liar Liar, and Dumb & Dumber any day.

Other American comedians have made much more successful journeys into dramatic territory recently. Despite having a face that is intrinsically hilarious, Jamie Foxx, a brilliant slapstick comedian, has been astonishingly good since he threw off his comic shackles, particularly in Collateral, as the taxi driver Tom Cruise takes hostage for a night, and in Ray, playing the blindjazz pianist Ray Charles, a performance that won him a best actor Oscar. Murphy surprised a lot of people with his turn as a machiavel-lian music manager in Dreamgirls, getting a best supporting actor Oscar nomination.

Even Will Ferrell, America’s reigning comedic champion, was entirely plausible playing it straight in Stranger Than Fiction, as a tax inspector whose life is being narrated by an author he learns is planning to kill him off. “It was so freeing not to run around and act like a crazy person,” he said about the experience. “It was so nice to be conversational and talk like a normal human being.” I still preferred Talladega Nights: The Ballad of Ricky Bobby. And I can’t bear Adam Sandler as a comedian — did you see Happy Gilmore? — but he is pretty good doing the drama thing in Punch-Drunk Love, directed by Paul Thomas Anderson, and believable as a 9/11 widower in his latest, Reign Over Me.

The problem for most of these comedians, though, is that once they have ripped off their clown mask and shown us the dark side of their soul, it is so much harder for us to find them funny when they try to pick up their comedic shtick again. The great comedians of the past knew that. One of Chaplin’s darkest films was Monsieur Verdoux, which he made towards the end of his career. He played a Bluebeard who kills rich women so he can support his ailing wife and son. It’s incredibly disturbing because it’s so funny. As Seinfeld’s Cosmo Kramer knew, and too many of today’s comedians forget, there’s nothing more terrifying than a clown.

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