Clark Gregg has one of those faces; you've seen him in countless TV and film roles, usually looking serious and determined and carrying a gun. He's played enough cops, lawyers, and FBI agents — among them a recurring role as Agent Michael Casper on "The West Wing" and his appearance as the mysterious operative looking to recruit the title character in "Iron Man" — to start his own task force.

It's a casting trend that amuses the 46-year-old Gregg and his friends. "I did kind of become the go-to guy for authority figures, which is something that everyone who knows me gets a really good laugh out of," he noted. "I guess I have an FBI face, I don't know."

At any rate, it's one that is becoming increasingly familiar, thanks to turns in films and his regular role as the wry ex-husband to Julia Louis-Dreyfus on the CBS comedy "The New Adventures of Old Christine."

But as he's gaining recognition as an actor, Gregg is also building a solid reputation behind the camera. It began with his script for the 2000 film "What Lies Beneath," the creepy ghost story starring Harrison Ford and Michelle Pfeiffer. Not content with conquering two professions, Gregg is now making his directorial debut with "Choke." The film, which opens Friday, is an adaptation of Chuck Palahniuk's twisted novel starring Sam Rockwell and Anjelica Huston.

Palahniuk's novels tend to be darkly humorous creations that defy definition — and are generally regarded as near impossible to adapt. The only one previously transferred was "Fight Club," directed by David Fincher and released in 1999. Describing the plot of "Choke" proves arduous, even for Gregg.

"It's what I would call a black romantic comedy," he said. "It's not an easy one to break down."

The plot centers around a sex addict named Victor Mancini (Rockwell) who purposely chokes at restaurants in order to be rescued by Good Samaritans he can then emotionally blackmail for money. The goodwill cash keeps his ailing mother (Huston) in a mental institution, where Victor becomes involved with a doctor (Kelly Macdonald) who believes Victor is a clone of Jesus Christ. And never mind his day job as a performer at a colonial village, where he earns the ire of the Lord High Charlie (Gregg, in a hilarious supporting turn).

Fortunately, Gregg never had to try to pitch the Byzantine plot. "It was brought to me as a novel to adapt, so I skipped many steps," he said. "I went crazy for it and pulled in every favor and begged and pleaded and threatened in order to make it myself."

Though he had appeared in a few high school productions, Gregg said he never thought he would become an actor. "I wanted to be in punk bands or be in trouble," he recalled. He played soccer at Ohio Wesleyan University until he dislocated his thumb, and on a whim he tried out for the school production of "Much Ado About Nothing." He landed the lead but didn't consider pursuing acting as a career, though he admitted, "It got under my skin a little."

He dropped out of school and moved to New York, and then his friend Mary McCann turned him on to a class being taught at New York University by David Mamet and William H. Macy. "It was there, working with those guys, where I first discovered acting could be something interesting and noble," Gregg said.

Gregg graduated from NYU's Tisch School of the Arts and, along with Mamet and Macy, was a founding member of Atlantic Theater Company. He remained busy on stage, appearing in "A Few Good Men" on Broadway and directing an acclaimed revival of Mamet's "Edmond," while also making trips to Los Angeles for film and TV work.

When a friend suggested he try directing for film, Gregg was intrigued. "I said, I'd love to, but how do you do that?'" he recalled. "They said, The best thing you can do is write a script.' So I started to write for that purpose."

His acting agent soon began representing him as a writer and sent out a supernatural-themed script Gregg had completed. "DreamWorks didn't want to make my movie, but they had a ghost-story idea, and they were interested in having me try to write that," he said, still sounding surprised. Gregg called his experience on "What Lies Beneath" "a two-and-a-half-year film school" and praised director Robert Zemeckis for "keeping me around and involved."

He also noticed that when one career began to flourish, the other followed suit: "The funny thing is, as soon as I started working as a writer, suddenly I started to get a lot more paying work. Before, I'd been doing a lot of theater or guest-star roles, and you can't stay alive too long doing that. Then I was sent Choke' and I remembered why I started writing to begin with: so that I could make a movie. And I said, Maybe this is the one.'"

He was drawn to the offbeat story and thought the fact that Palahniuk wrote in such a filmic way would make adapting it easier. He was wrong.

"The only conversation I had with Chuck, he said, I'm just going to give you one hint: Don't be too faithful to the book.' I thought, That was nice, but he had to say that,'" Gregg recalled. "I told myself, There is so much funny, visually fascinating stuff in here; I'm just going to kind of do a cut-and-paste and turn it into a screenplay.' Then I spent a year and a half struggling." It was only after he decided to lose the first-person narrator and throw the book in the drawer that the screenplay began to take shape.

Once he had a script in place, Gregg knew he had to find the perfect leading man to win the audience over.

"This script was something that made people uncomfortable, and Victor does a lot of sketchy, sleazy things," he noted. "It was clear I needed someone who wasn't a lothario type and you could really care about." He had met Rockwell when they performed together in 1991 in the play "Unidentified Human Remains and the True Nature of Love" and offered the part to Rockwell, who clicked with the "Choke" script immediately.

Gregg shot "Choke" in 25 days in July 2007 while on hiatus from "The New Adventures of Old Christine." The film premiered at the Sundance Film Festival in January, earning a Special Jury Prize for best work by an ensemble cast.

Gregg isn't sure how the rest of the world will react to "the demented comedy about the sex addict," but he has plenty of other projects to distract him. He recently began work on the fourth season of "Old Christine" and is starting to write an ensemble piece to direct.

"That is, if they'll let me after this one comes out," he said. "This next one may be as twisted as Choke,' and I don't have Chuck Palahniuk to blame this on."