Tom Cruise said playing heroic loner Jack Reacher was "easy" because it reminded him of his own life.
The Top Gun star spent hours meeting fans at the premiere of his new film in London's Leicester Square.
Jack Reacher is based on One Shot - one of the series of best-selling novels by Lee Child about the eponymous former soldier turned drifter who travels the United States dealing out his own brand of justice.
Tom said: "It was easy, it was just a great character to play.
"That's kind of my life actually you know, making movies I'm here in London for four months and I shoot in Pittsburgh, Baton Rouge and Italy. I spend that kind of life making movies."
Child - real name Jim Grant - said he knew Tom was the right man for the role when he saw him carry on with work on set despite a serious hand injury.
The author, who was born in Coventry and grew up in Birmingham, said: "He's reckless like Reacher."
Tom's co-star Rosamund Pike said she loved working with the man she described as "the greatest movie star of my lifetime".
She said: "I was on my stomach watching Top Gun aged 12, 13 and it was very exciting to work with a guy who is still on top of his game, and into the room walks the man who created all those iconic parts and he doesn't disappoint on any level."