Producer Brian K Vaughn Leaves "Under the Dome"

CBS' monster hit Under the Dome is losing one of its key players.

Writer/executive producer Brian K. Vaughan has exited the summer sci-fi series, The Hollywood Reporter has learned.

Vaughan was handpicked by exec producer Steven Spielberg to adapt Stephen King's best-seller when Dome was in development at Showtime. When the premium cable network passed on it and the sci-fi show about a town trapped under a mysterious dome was picked up straight to series at CBS, ER alum Neal Baer was brought in as showrunner.

Sources tell THR that it was Vaughan's decision to exit the series; he arced out season two with Baer before his departure. Vaughan penned the pilot episode as well as two other installments, including the season finale, which he co-wrote with Scott Gold. Vaughan's decision to exit the series was described as amicable, with the veteran comics scribe said to be more interested in spending time with his family and returning to focus on his graphic novel roots. Dome was Vaughan's first TV gig since he served as producer, writer and exec story editor on ABC's Lost.

On the comics side, Vaughan launched his newest comic, the critically praised Saga, in 2012. His credits include the acclaimed Y: The Last Man, Ex Machina and Runaways.

"Right after we finished season one of Under the Dome, our showrunner Neal Baer and I had the amazing honor of working with Stephen King himself to help plot the new direction of our second season. It was one of the best experiences of my creative life, but it was also a really long time to be apart from my family, who I've seen way too little of since I started helping to develop Dome years ago, so I decided to step away from the show," Vaughan said in a statement. "I really miss the cast and crew, but it's awesome to get to see my kids again and catch up on my comic-book deadlines. I'm very grateful that CBS and Amblin gave me this opportunity to help adapt one of the best novels ever by my lifelong hero, and I'm excited to watch all of my friends' hard work come to life in a few weeks."

Dome was a breakout hit for CBS last summer. The drama, which was billed as a limited "event" series, launched to a summer best with a 3.2 rating among adults 18-49 and 13.1 million total viewers, ranking as the biggest audience for a drama launch in the past year. CBS touted Dome during May's upfront presentation as the 2013-14 TV season's most-watched new broadcast series and one of the three most-watched dramas in the world (joining NCIS and CSI). Vaughan, who spoke regularly about the series, was not among the panelists at CBS' Summer Press Day in May, where Baer was the lone producer on the panel.

In a September interview with THR following the critically maligned season-one finale, Vaughan said he was "proud" of what the series had accomplished and vowed that its sophomore run would be different. Asked if there was anything he would have done differently creatively, Vaughan said: "I think there are always things -- the speed that you'd put together a new show with and the fact that we had 13 episodes just about completed in their entirety before one had even aired. Looking back, sure, there are always things you'd do differently. For the most part, we concentrate on the parts of the show that we really liked and challenge ourselves to do something new next season."

Season two of Under the Dome kicks off Monday, June 30. King, who has a cameo in the premiere, penned the return episode and continues to be an exec producer.

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