According to IMDB, Cerone wrote for DEXTER during its first and second seasons, and was a credited executive producer from the second episode of the first season to the season three finale.
James Manos, Jr. was in charge of DEXTER during its first season, as the developer and (as far as I can find online) showrunner.
Clyde Phillips took over as showrunner in season two and left after season four (he joined the series as a writer in the second episode of the first season).
Chip Johannessen (late of 24) was the showrunner during the latest season. He's being replaced by Scott Buck, who has written and produced for DEXTER since its second season.