Woody Harrelson was "concerned" about portraying a stereotypical villain in 'War for the Planet of the Apes'.
The 55-year-old actor had long discussions with director Matt Reeves about how to ensure his portrayal of The Colonel in the rebooted sci-fi franchise was "more human" than how evil characters tend to come across on big-screen productions.
He said: "That was a big concern of mine. Because when I read it I thought it was a little more black and white.
"I talked to Matt about ways to make the character a little more human.
"I think The Colonel thinks that what he's doing is what needs to be done to save humanity so from his perspective what he's doing is right and just.
"It's good to have it not be so black and white."
Harrelson was "staggered" to see how well the movie, which uses motion capture technology to bring the ape characters to life, looked when it was completed, and praised Andy Serkis for his "phenomenal" performance as chimpanzee Caesar.
Speaking to Collider, he added: "I was pleasantly surprised when I saw the finished product. It's so different from what's happening.
"Andy is a phenomenal actor and he's got all these dots on his face, and he's got the camera, the grey suit, you believe he's an ape.
"It's his eyes, his voice, his mannerisms, his movement, he's doing the performance.
"But when it all comes together it's pretty staggering. The level of what goes into that CG. It was so realistic and so well done. These guys are the best in the business. "
The motion picture also features Karin Konoval as Maurice, Caesar's advisor, and Steve Zahn as Bad Ape.