Ari Gold, from the HBO series Entourage, is by some distance the most compelling comedic character on television, and possibly any other art form, today. Ari is the motor-mouthed, profane, ego-fuelled agent of the show’s nominal hero, Vincent Chase, an actor simply too beautiful to fail in a world that likes its surfaces to shimmer. But Ari takes us beneath those surfaces, showing us the relentless aggression that is needed to make it in show business. He wants, in the words of Jeremy Piven, the actor who plays him, “to rule Hollywood. He really wants to rule the world, but he’ll settle for Hollywood.”

Piven, a triple Emmy-winner, is in London this week promoting the latest DVD in the series and catching up on his great love, the theatre. Plenty of movie and television actors say this, but Piven means it. Check out one of his improbable inspirations for his portrayal of Gold: “Twenty years ago I was studying in London at the National Theatre – there was this amazing scheme for American actors, we did Shakespeare seven days a week and went to the theatre every night,” he tells me over a cappuccino in Soho.

“I remember seeing Antony and Cleopatra with Anthony Hopkins and Dame Judi Dench – and she came on stage with such presence ... It would have been like acting opposite an animal which had escaped from the wild, that’s how powerful she was. The way she used the space, like no other actor I had ever seen. I was blown away. And it was part of my inspiration for Ari. I’m sure she would be offended if she heard that.”

Doubtful, I say. Ari is a kind of hero, not least to certain readers of this newspaper who love the sharp suits, the pitbull violence, the scabrous humour. (“Let me be heard this time,” he implores Vince, “and I swear to God you will be stronger than you ever were. Like Lance Armstrong but with two balls.”) I ask Piven where he pitched Ari morally.

“As an actor, you can never judge your characters,” he says with something approaching loyalty to his alter ego. “I think some of the readers you describe would be very disappointed in Jeremy Piven the person as opposed to the character he plays. I grew up in a stage family, I was butchering Chekhov at eight, I have been doing yoga for 15 years and I’m trying to find some balance in my life. Ari is a shark in every sense of the word. A killer. I have to whip myself into a frenzy to play him. But I love it, it’s cathartic. It is the role of a lifetime.”

HBO has been at the vanguard of what has turned out to be a golden age of television, creating not only the best drama the medium has ever seen with The Sopranos and The Wire, but a host of format-busting comedies that has taken scripts and performances to a new level.

Piven had a minor role in one of these, The Larry Sanders Show, which was the network’s first piece of original programming. “I was a stage actor in Chicago and being sent a lot of TV scripts that just weren’t funny,” he recalls. “And then Larry Sanders arrived and it was this whole other thing: insightful, layered, its characters were self-conscious and tragic – I wanted to be in on it from the start. We knew then it was completely revolutionary.”

So when it came to Entourage, he says, “we knew we were in good hands”. I say that the show’s masterstroke was to offset the passive Vince with the alpha-male predator that was Ari, giving it its yin-yang dynamic.

Piven looks dubious for a second. “To be honest with you, guys like you give us too much credit. Ari was only ever meant to have one scene per episode, the comedy was supposed to be about these guys getting laid because their best friend was famous. But it evolved. It was a beautiful accident. We got lucky.”

Returning to his first love, he says he wants to act in the West End. “When I was studying here, I asked a casting director if it was ever possible that an American actor could work at the National, and she laughed and said there was no way, you would have to be a star. And I remember being so stupid and so green, that I thought, OK, I’ll try and do that. I’ll go running back, get some kind of profile, and come back and work on the stage.”

He recently saw Keith Huff’s Broadway success A Steady Rain, starring Hugh Jackman and Daniel Craig, and says he would love to come to London with it: “I’ll plant that seed right now.” His own recent Broadway experience, in David Mamet’s Speed-The-Plow, received glowing reviews but ended unhappily when he couldn’t complete the run because of illness (he was unsuccessfully sued by the producers).

“I did four months, and then I got ill, and doctors told me I needed to stop: I had a resting heart-rate of 47, Epstein-Barr, a level of mercury they had never seen. There was no broken contract – if you are ill, you can’t continue. I’m not going to beat myself up about it.”

Is he receiving a lot of inferior Ari-type characters to read? “The best thing I got recently came from a British producer. It takes a Brit to spot that really I’m just a soft, sensitive, stagey Kumbaya, yoga-doing freak, a poof from f****** Chicago.” Weirdly, he sounds a little like Ari as he says this. “I could play that tomorrow. I did 40 movies before Ari, a lot of also-ran best friends who were not type-A guys. I have a pretty wide range.”

He says Entourage has two or three series left in it “before we start repeating ourselves” (HBO has just green-lit the seventh). I wonder how many plot twists it can take, and he says gleefully: “I would love to see Ari brought to his knees. It could be done in a beautiful way. Why not? Let’s explore every option. I’d rather go out swinging, dying on my shield ... ”

peter.aspden@ft.com
More columns at www.ft.com/aspden