Michael Keaton fans have come to expect the veteran actor to continually do variations on the kind of roles he’s played since he first burst onto movie screens 35 years ago in “Night Shift” — offbeat, unpredictable, often comedic characters. Early on, he tried and was successful at being menacing in “Pacific Heights,” and there were a number of straight-ahead dramatic parts and, in the cases of “Jackie Brown” and its companion piece “Out of Sight,” some edginess. Yes, he played a villain in the “RoboCop” remake and a super-villain earlier this year in “Spider-Man: Homecoming.” But in “American Assassin,” the first of author Vince Flynn’s popular series of Mitch Rapp thrillers to be adapted into a movie, Keaton gives us a very out-of-character, no-nonsense tough guy: Stan Hurley, the head of a clandestine American agency that trains agents to take on and wipe out terrorists. (Rapp is played in the film by “Maze Runner” star and up-and-comer Dylan O’Brien).

Keaton recently spoke in Los Angeles about climbing into the shoes of Stan Hurley, what suggestions he contributed as far as shaping the character, and his thoughts about the multiple books in the series becoming a film franchise.

Q: You haven’t played anyone quite like this before, anyone this tough. Hurley has to make some pretty harsh decisions. Were there any lines you felt you couldn’t cross?

A: I’m not a believer in playing someone who, for simplicity’s sake, is the bad guy. Like Ray Kroc, who I played in “The Founder.” It’s not that Ray is a bad guy, even with what he does at the end of the film. But the agreement that I had with (director) John Lee Hancock in that film was that I was interested in only one thing: That I don’t pull back. But you also work within the framework of “what’s the story, what’s the picture, what are you trying to accomplish?” There’s actually a lot of Stan Hurley that I like, and that I probably agree with.

Q: You’re a politically engaged guy. Did this film speak to you or connect with you on that level at all?

A: It was actually a concern. I think the result is good, but frankly I was a little bit concerned about how it leaned. I’m not one thing or another (politically). I don’t think most people are. In terms of the terrorism issue, I would call myself somewhat of a hard-liner, to say the least, but maybe not so much in other areas. So, I was OK with what the goal was in the books and in the movie. That said, one of the main concerns of both Dylan and I when we first read the script and were talking about maybe making this movie was that it wasn’t simplistic or black and white. You didn’t go down the traditional path of path of these kinds of people from this part of the world. So, to the credit of (director) Michael Cuesta and (screenwriter) Stephen Schiff and whomever else took our notes, they made it more complicated and interesting and not as cliched. It was more palatable to me once they accomplished that.

Q: So, since you had some hesitations of what the movie was going to be, where did you start as far as developing the character?

A: It wasn’t very complicated. After talking to the producers and the director, they were pretty clear on what kind of movie they wanted to make. Once you sign on and say to yourself, “I’m in THAT type of a movie,” you then say, “OK I’m all in.” It’s foolish, as an actor, to say I’m really going to make my own little movie. You’ve signed on for the movie, and we’re all telling the same story, and right there, things get really simple for me. I did read the book. I didn’t think I was going to do that because a lot of times I say, “Well, we’re shooting the script. I’m basing everything on the script. This is the blueprint.” That’s the way I believe in working, and it’s really practical. But I decided to read the book because I wanted to get the essence of it. It was actually quite helpful. You say how does this character function in the movie? What kind of movie are we making? Then you do the basic work: Where’s he come from? What’s his background? Really fundamental stuff.

Q: There are 16 books in the series. Did you sign on for the film with the idea that this is perhaps a franchise?

A: You mean, like in cartoons, did I get those dollar signs over my head? Yeah, kind of. (laughs)

“American Assassin” opens on Sept. 15.

— Ed Symkus writes about movies for More Content Now. He can be reached at esymkus@rcn.com.