Since the film's release in 2007, the Scottish-born actor has gone on to star in the romantic drama, P.S. I Love You, Guy Ritchie's gangster movie, RocknRolla, the romcom, The Ugly Truth and all-action flick, Gamer.
Such an eclectic mix of roles has proven Gerard's chameleon-like quality and is one of the reasons he can now command a reported $15 million per movie.
His box-office clout was a deciding factor in his choosing to produce, as well as star in, his latest movie, a crime thriller called Law Abiding Citizen.
"There comes a time when you get a lot more say in which movies are going to be made and movies are made off your back, so then you want to be a little more involved and get some credit for it," says Gerard, his Scottish accent still intact despite being based in Los Angeles for most of the year.
He's wearing jeans and a leather jacket, which he removes during the interview to reveal a long-sleeved T-shirt which hints at the impressive physique that made his name. Candid, chatty and prone to swearing intermittently, he's just turned 40 but looks a five years younger despite admitting he's only had three hours sleep.
In Law Abiding Citizen, Gerard plays Clyde Shelton, an honest, upstanding family man whose life is left in tatters when his wife and daughter are brutally murdered. Starring opposite him is Oscar-winning Jamie Foxx who plays Nick Rice, a young and ambitious prosecutor. When Nick cuts a deal that spares one of the killers from death row, it proves a catalyst for Clyde to seek vengeance on the legal system and everyone who has let him down.
"There's one thing I've learnt as an actor, as well as producer, and that's to trust my own instincts," he says. "When I first started acting, I would have an idea about certain things, whether it was a scene or some dialogue and often it wouldn't be followed through but I was never in a position to have the power to press the matter. When the movie came out, my agents would say, 'Do you know what, that was a good point you had there'. I noticed the more involved I became in developing stories, the more I realised I could actually have a huge amount of input."
As for whether his candid approach created problems for his past directors, he just laughs and says, "Yes, absolutely but then it can be a pain in the ass for an actor and producer if there's a director that doesn't listen."
Gerard first came across the story for Law Abiding Citizen when a script writer cornered him and begged him to read his script. The story may have been pretty raw but Gerard recognised its potential.
"It was two years of slowly but surely getting this thing going and working on the script and developing it," he says. "I had so much to do about how the story turned out and in actual fact some of the mistakes that were made were the few areas where I didn't stand up for myself, where I felt I wish I had believed in myself more there and trusted my gut."
He catches himself before divulging exactly what these mistakes were, although he does reveal, "positions were filled but tasks weren't fulfilled".
"That caused the movie to take a lot longer to be made and cost a lot more money than it should have. The strange thing is, when it all came together, every possibility had been analysed a thousand times over, so it felt like it made the movie stronger in the end," he explains.
Initially, Gerard was going to play Foxx's character "but as time went on the more I was becoming seduced by the role of Clyde," he says. "I've often played the more heroic character with a more straightforward journey and I kind of wanted something I could get my teeth into."
His greatest challenge was turning what was a two-dimensional character in the initial draft, or as Gerard puts it, "a man who went from this kind of lovely, comfortable suburban husband to this bitter, twisted, annoying d**k," into a fully-rounded, complex character.
Working with criminologists on the psychology that drives revenge killers, Gerard says it's about climbing into the mind of person who has been wronged.
"Everything in his life has changed in one moment. What must that be like and what kind of lengths would you go to as a person to take revenge and answer back?"
Be warned that Clyde goes to violent and bloody lengths.
"What was cool was there was nobody who was trying to shy away from the violence," says Gerard. "Everybody realised that's what was going to make this movie and make it stand out."
A law student for seven years before he turned to acting, Gerard says that experience was one of the reasons he was initially attracted to the movie.
"Having been involved in the law and then realising I no longer wanted any involvement in it and then coming across this story, which is really an indictment of the legal system or the way it can be abused.
"But then as much as we talk about the analysis of the legal system, I guess it gets to the point where it's just pure entertainment. There's a huge popcorn element in this movie," he says.
"It hits a certain level and you go, 'Okay, I've just to go and have fun with this' and at that point we were pushing every bit of violence that we could. In actual fact there a couple of things we had to take out of the final cut."
Apparently, one such scene was so graphic, Gerard says: "There were guys who had worked in the film industry for 30 years in front of the monitor with their hands over their mouths."
Gerard admits that portraying a serial killer along with dealing with the problems he faced as a producer meant he wasn't always in a good space when shooting the movie.
When filming finally wrapped, he decided to return to Scotland where he "went away on my own a lot, climbed up a couple of hills and got a tent out."
It's a world away from 'Gerard the play-boy' we read about in the tabloids. Appearing to enjoy the life of a bachelor there have been reports of him dating a number of Hollywood ladies, including Jessica Simpson and Jennifer Aniston, his co-star in the upcoming movie The Bounty.
As for what he thinks about being tabloid fodder, he laughs and says, "I try and stay away from reading anything and if anybody sends me clips or articles or tells me what's going on, then I normally tell them to leave me alone. It's normally when I'm doing press that people say, 'Oh, so is it true about...? That's when I catch up on all the rumours!"
Extra time - Gerard Butler
He was born in Glasgow on 13 November 1969 but was raised in Paisley, Scotland.
His stage debut was at the age of 12 in the musical Oliver.
In 1996, he landed the lead role in the stage production of Trainspotting.
He made his film debut as Billy Connolly's younger brother in Mrs Brown, starring Judi Dench.
He showed off his singing skills when he played the Phantom in the movie version of Phantom of the Opera.