It was recently announced that Michael Rooker and Norman Reedus had joined the cast as brothers Merle and Daryl Dixon. Neither character appears in the Image Comics series on which the show is based.
"They're my invention, actually," Darabont told IGN. "Michael has a brief but rather potent appearance. But Norman is kind of hanging in now as one of the ensemble cast members. His character is working out really interestingly. He's a bit of a wild card in the mix and that's great."
Darabont explained that he had decided to include new characters in the adaptation in order to keep the show fresh and surprising.
"I love maybe throwing an extra character or two in, that's really going to shake the ingredients up a little bit more," he said. "Put you a little bit more off your feet or on your guard, you know? I think [that's] kind of interesting."
The director previously insisted that the series would remain faithful to the comic book.