Michael Fassbender has become one of the world’s biggest stars, yet he’s still humble enough to appear in an independent art-house film or on stage at a comedy festival for a one-off reading of a cult classic. He’s Hollywood, but with a twist of Hackney. In fact, he even has a flat in the latter.

It’s easy to forget that the 38-year-old started his film career as an action hero – a spear-wielding Spartan in 300, the fantasy epic (with the emphasis on ‘epic’). Before that, he caught the eye with his turn in Steven Spielberg and Tom Hanks’ Band Of Brothers TV mini-series. But his association with Steve McQueen – avant-garde artist turned Oscar-winning director – along with a series of exceptional career moves mean that he’s now rightly considered to be one of the finest actors of his generation.

Turns in X-Men and Prometheus haven’t nulled Fassbender’s penchant for the leftfield. And even the characters he plays in the bigger films have a touch of danger about them. When it comes to his career choices, he puts it succinctly: “I like taking risks.”

Today he’s here to discuss the upcoming Macbeth movie adaptation, in which he plays the titular character alongside the incomparable Marion Cotillard. Shakespeare is a whole new ball game for the German-born, Irish-raised star. Actors often talk of taking on challenging roles, but Fassbender picks characters that are as challenging for the audience as they are for him. You rarely like someone he is portraying. In person, he’s bright, chatty and enthusiastic, which is slightly disarming. You’re used to seeing him playing unspeakably horrible or, at best, violently conflicted characters on the big screen. Compared to Shame and 12 Years a Slave, his latest role is almost light-hearted.

“It was a great opportunity to play Macbeth,” Fassbender says. “It was a rare privilege for me to be able to do a Shakespeare play and Macbeth happens to be my favourite of his works. Both the language itself and the character are so daunting that it’s almost as if you’re being dared to take it on. I like taking risks, and this was one I couldn’t pass up.”

He admits, though, that it was never a dream of his to do Shakespeare – and considers himself far from being a theatre actor, which is a surprise, given his pedigree.

“I had done Shakespeare in drama school and never really imagined that I would do a stage production or work on a film adaptation. It was quite accidental but I saw Macbeth as an opportunity to do something very different from my other work of late.

“Reading the lines in iambic pentameter was one of the more difficult aspects of mastering the text. I would keep repeating the lines over and over until I felt that I had mastered the rhythm,” he says. “I approached Shakespeare’s text as if it were music; you try to make the melody part of your speech pattern. But my thinking was that the rhythm is there to amplify the meaning and emotions of the words and in the process of acting. I hope that I got the rhythm right.

I saw Macbeth as an opportunity to do something very different from my other work

“I wouldn’t consider myself a theatre actor by any means. I did some popular theatre, including an adaptation of Quentin Tarantino’s Reservoir Dogs when I was around 18 years old. Playing Macbeth is a far more difficult proposition than anything I ever did in theatre when I was younger.”

He reserves special praise for Cotillard, his French co-star. “I was very impressed by how brave she was to do Shakespeare given that she’s French-speaking and has to master a particularly difficult form of English speech.

“I can’t imagine myself speaking French in an adaptation of Voltaire, for example!” he laughs. “Marion does a brilliant job, though. She makes the process seem so natural and she brings an incredible intensity and subtlety to her work. She is also so present in her acting that it’s almost frightening.”

He chats away about his passions – Formula 1, karting, motorbikes – drawing further contrast to the dark art he produces. So how is someone so sprightly so keen to play such macabre roles?

“It might be because I’m really mad myself!” he laughs. “But I’m not mad enough to allow that to destroy me. I think we’re all a little mad and it’s more interesting to acknowledge and portray madness than to ignore it. If you look at how we behave on this planet there is no doubt that madness is everywhere.

“When I look at the roles I seem to be drawn to, you can see something of a recurring pattern at work. I don’t know whether directors or producers see me as a tortured soul. Maybe they do? I guess I have that tortured look about me. I think it’s time for me to start doing more comedies...”

Of course, one of Fassbender’s best-received roles so far was a comedic one: the titular Frank, based loosely on Chris Sievey’s Frank Sidebottom musician persona, but even that had its fair share of dark moments. It points towards the fact that his characters are never one-dimensional: they’re often conflicted and compulsive, the tortured or the torturers.

I don’t know whether directors or producers see me as a tortured soul. Maybe they do? I guess I have that tortured look about me

There’s no escaping that his darkest (and arguably most famous) moments to date have been in McQueen films: as the sadistic slave owner in 12 Years A Slave, the sex-addicted high-flyer in Shame and Bobby Sands, the IRA leader starving himself in Hunger. It’s testament to his acting ability – and McQueen’s direction – that the characters are so different, but each of them are propelled by something: be it hate, love, lust, politics, anger or all five.

He denies that he spends too much time contemplating how tormented a character is before he agrees to play a role, but it’s clearly something that he’s drawn to. All this darkness – does it ever worry his parents? What do they think of his acting career?

“My parents are especially proud of my work,” he says, before revealing how differently things could have turned out. “After I abandoned the idea of being a guitarist in a heavy metal band, they were rather nervous when I told them I wanted to be an actor. They didn’t see it as a secure profession. They were relieved when I finally started to have some success and now they’re retired they often come to visit me on set. That means a lot.”

Fassbender is regarded as a sex symbol even though he often plays rather unappealing characters. Although it’s a strange contradiction, he’s not too bothered about it. It’s not exactly a status with many downsides.

“I’m happy in my skin, and I never think about whether my characters are unsympathetic or tormented in terms of wanting to play those kinds of roles. I look at every part as a way of expressing different aspects of their humanity,” he says. “I have no vanity when it comes to that. That’s what I love so much about acting – the ability to submerge your ego into that of another person.

“And the whole notion of being a sex symbol is a bit frightening and ridiculous – although it suits me!” he laughs.

Born in Heidelberg, Germany and raised in Killarney, Ireland, the 38-year-old actor got his first break in Band of Brothers (2001), and then went on to appear in both series of Hex on Sky One. From there he appeared in a few plays and even a Cooper Temple Clause music video. Soon after he found mainstream success as Stelios, a young Spartan warrior, in 300.

Recently he’s made the move towards production and worked on Slow West – a western directed by John Maclean (formerly keyboard player in the short-lived but critically hailed Beta Band), which certainly hasn’t done his indie credentials any harm.

As you might suspect, Fassbender is more New York than LA – and splits his time between there and his London flat in Hackney. He’s been dating Alicia Vikander, the fast-rising Swedish actress he met on the set on The Light Between Oceans, since late 2014, and if the tabloid pictures are anything to go by spends much of his time partying and watching Formula 1. In fact, for a man who goes from success to success in his movies, he finds a lot of time to travel Europe.

When we bring up motor racing, it’s like he’s been waiting to talk about it all day. He says he’s “probably” addicted and adds that his twin loves are karting and motorbikes.

“Karting is an experience that is about as close to being in a Formula 1 race car that you can have without killing yourself. I love the feeling of being so close to the ground, which is something you don’t get when you’re driving a car. I enjoy the sensation of the speed and the turns and the G-forces in karting even though it’s nothing compared to what Formula 1 drivers experience. Being on a motorbike and concentrating while you’re going as fast as possible is also a strange form of relaxation – your mind just adapts to what you’re doing and you stop worrying about everything else that’s going on in your life.”

He also reveals an unlikely love of karaoke. “I love it,” he grins. “But I’m not sure I would have many fans left if they came to hear me. I’m totally fearless when I take the microphone. I’ll sing Sinatra or the Rolling Stones or Creedence Clearwater Revival without any shame or regret! It all depends on my mood and especially the number of drinks I’ve had that evening.”

Next up for Fassbender is the Danny Boyle-directed Steve Jobs, in which he plays the late Apple founder. The actor reveals a deep appreciation of his subject, explaining that he “worships Jobs’ intellect” – but claims he’s personally not clued up on cutting-edge tech.

“He was an extraordinary man who changed the way we live on so many levels,” he says. “But I’m something of a caveman when it comes to technology, so it was quite an education for me to prepare for the film. I also discovered that Steve Jobs was also instrumental in introducing the Apple stores at a time when the industry was worrying about online sales. The man was remarkable and certainly ahead of his time.”

I’m something of a caveman when it comes to technology, so it was quite an education for me to prepare for the film

You’d like to think that Fassbender might have invested in some new gadgets after his work on the movie, but he lifts up his battered phone and laughs. “No – I’m still using my iPhone 4. I love the design of it and I’m going to keep using it until it dies.”

The film is produced by Scott Rudin, and written by Aaron Sorkin, who adapted Walter Isaacson’s biography about the Apple founder, while Kate Winslet, Seth Rogen and Jeff Daniels co-star. At this point, all we’ve seen is the official full trailer, which was released in July, but many are already predicting a long-overdue Oscar win for Fassbender even before the movie has come out.

Next year will also see release of the next X-Men instalment – with the actor reprising his role as Magneto, the most mainstream and, perhaps, high-profile character of his career.

It would be easy to say that it pays the bills and the other roles keep him happy, but you get the impression that’s actually not the case.

Fassbender is a man motivated by taking on the most complex and interesting characters he can, and picking and choosing his roles carefully. He’s at a level that most actors dream of – and one that most don’t arrive at until they’re in the twilight of their career. In fact, he’s seemingly always been there.