EXCLUSIVE: There will be a change at the helm of Showtime’s flagship drama Dexter for its upcoming sixth season. The series’ executive producer Scott Buck has been named new showrunner. He will succeed Chip Johannessen, who ran the show last season. Dexter‘s fifth season, which concluded on Sunday, ranks as the highest-rated season of the drama series to date, averaging more than 5 million viewers per week on TV and on-demand. And while Johannessen is well regarded, the feeling was that Buck, who had been on the show since the second season, serving as No.2 to Johannessen and previous showrunner Clyde Phillips, was ready to take the reins of the series, which landed several Golden Globe and SAG nominations this week. Buck also has had great rapport with the show’s writers, all of whom are returning next season. Buck joined Dexter at the beginning of Season 2 as a co-executive producer and was upped to executive producer at the beginning of Season 4. He has written or co-written the last three season finales, including the one that aired on Sunday. Before Dexter, WME-repped Buck was a writer/producer on HBO’s Six Feet Under.