You’ve seen him in movies and on TV. He’s that smarmy, balding, authoritative guy in State and Main (2000), In Good Company (2004) and this year’s blockbuster Iron Man (2008); on the hit CBS sitcom “The New Adventures of Old Christine” he plays Julia Louis-Dreyfus’ ex-husband. Yet, what you might not know is that he’s also a founding member and former artistic director of the Atlantic Theater Company in New York and made his screenwriting debut with the successful 2000 Robert Zemeckis thriller What Lies Beneath, starring Harrison Ford and Michelle Pfeiffer. On September 26th, Choke, his directorial debut and one of the most talked about movies at this year’s Sundance Film Festival, will be released into theaters. What’s this versatile guy’s name again, you may ask? Meet Clark Gregg.

Choke, based on Chuck Palahniuk’s (Fight Club) acclaimed novel of the same name, stars Sam Rockwell as a seriously disturbed man—a sex-addicted con artist who pays for his Alzheimer’s-afflicted mother’s hospital bills by faking that he’s choking to death in restaurants, preying on the sympathies of those who supposedly “save” him. Oh, and he also spends his days working at a colonial theme park.

This quirky character study was something of a passion project for Gregg, who also wrote the script and worked on bringing it to the screen for several years. “I had never read anything so painful and yet also so funny. I know Chuck is usually seen as this dark, nihilistic writer but I saw more than that in Choke,” Gregg says. “I felt the story was actually very hopeful and romantic, in its own perverse, post-modern way… For me, the book hit that chord where I thought, ‘I have to make this; nobody’s going to let me do this but I’ve got to find a way.’”

Gregg actively pursued writing and directing the dark comedy, a risky undertaking since he’s known more for his acting than his behind-the-scenes work. “Chuck was very patient because it took me a year and a half, two years maybe, and a couple of drafts before I could really get a handle on taking this surreal, satirical world from the page to the more three-dimensional realm of a movie,” he recalls.

In order to successfully adapt the novel, the writer-director had to focus on its emotional core. “There was something about the story that always felt painfully familiar,” Gregg says. “Along with its themes of sexuality and obsession, I found it to be a really heartbreaking story about the way people recover from emotional trauma in their lives so that they can give and receive love.”

He also felt it important to keep the odd tone of the novel, one in which comedy and tragedy co-exist. “One of the things that constantly drew me to the material was how it managed to have scenes that I found hysterically funny in a black comedy vein and then, two minutes later, there would be a really heartbreaking exchange that felt like Chekhov. In retrospect, I didn’t realize how difficult a balancing act it would be to make it work on those trenchant dramatic levels and still have it be funny. It was a wonderful challenge.”

It appears that challenge has paid off, with a Special Jury Prize win and Grand Jury Prize nomination at Sundance and a distribution deal with Fox Searchlight that sees Choke hitting theaters this weekend. With the release of the movie, Gregg has successfully transitioned from an intense, prolific character actor to a risk-taking, accomplished moviemaker.