The 46-year-old "Interstellar" star discloses that they didn't want the character of Walter to be "overly fantastic," reported Femalefirst.
"Well, he is a man, actually. They wanted to go very human and grounded with this. Obviously, there are mythical proportions of good and evil in Walter," the Oscar-winner actor said.
"The Dark Tower," based on the book by Stephen King, is an upcoming 2017 horror film that also stars Idris Elba in the lead role.