Depp, who stars as Jack Sparrow, explained to Rolling Stone magazine: "He was one of the people I admired for what he's done and how he's handled it. Forty-whatever years of being this god. And he's just cool."
The guitarist makes a short appearance as Sparrow's father, Captain Teague, in At World's End. Richards commented: "It was the right place at the right time with the right guys.
"Me, I'm just a musician. And if the people like my stuff, thank God. It pushes me on to do more. And I want to do more. That's something that you don't factor in when you start this game."