Andy Serkis asked his agent to put him up for "something decent" when he was first approached about appearing in 'The Lord of the Rings' franchise.
The 60-year-old actor was told movie bosses wanted to see him about a voice role "for a digital character", which didn't appeal much to Serkis, but he became more interested when told he was wanted to portray Gollum.
At a Fan Expo San Francisco panel, he said: "When I was first approached to play the role, it was explained to me by my agent when I first spoke to them on the phone about it.
"They said, 'Look, they're making this little film down in New Zealand called Lord of the Rings, and they want to see you for a voice for a digital character.'
"And I was like, 'What? There must be a dozen good roles in that movie.
"Can you not get me up for something decent?' And they said, 'Well, it is Gollum.' And I said, 'That's a decent role. Yeah, okay, alright, I'm listening.' "
Serkis initially thought he would just be the voice of Gollum, but director Sir Peter Jackson introduced him to motion capture technology.
He said: "But originally, it was explained to me that it was just going to be the voice. And then when I met Peter Jackson and auditioned, he explained that they were just on the verge of trying out this new technology called motion capture, and that he wanted an actor to be on set to act with the other actors. Because up to that point, many CG characters were only represented by a tennis ball on a stick, and the actors had to pretend that they were having a relationship with it.
"Gollum, as many people know, drives a lot of the scenes and drives the wedges between Frodo and Sam, and it's all about the interaction. He wanted an actor to play that character.
"Motion capture aside, I just approached it like any other role, getting into the psychology and the physicality and then the voice.
"And none of those could be separated for me. I can't just come up with a voice; it doesn't work like that for me as an actor.
"So, I started to think about the guilt that Gollum felt from killing his cousin and how that guilt was trapped, and I decided it was trapped in his throat. Then that kind of involuntary action helps propel the sound of Gollum."
In May, it was revealed Serkis is returning to the 'Lord of The Rings' franchise to star in and direct a new movie based around his character Gollum.
The actor is stepping behind the camera to take charge of 'Lord of the Rings: The Hunt for Gollum' - the first of several new films in the series being planned by Warner Bros. - and Jackson is to produce alongside his longtime writing partners Fran Walsh and Philippa Boyens, who will pen the screenplay.
Andy said in a statement: "Yesssss, Precious. The time has come once more to venture into the unknown with my dear friends, the extraordinary and incomparable guardians of Middle-earth Peter, Fran and Philippa.
"With Mike and Pam [Warner Bros chiefs Mike De Luca and Pam Abdy], and the Warner Bros team on the quest as well, alongside [special effects company] WETA and our film making family in New Zealand, it’s just all too delicious…"
