EXCLUSIVE: Family Guy veteran Steve Callaghan is joining American Dad as executive producer and new showrunner. In the showrunner duties, Callaghan succeeds American Dad co-creators Mike Barker and Matt Weitzman who remain executive producers on the series. The changeover is part of Seth MacFarlane‘s strategy of keeping things fresh on his Fox/20th TV animated series by shaking things up at the top. MacFarlane is also known for deep loyalty to his writers, most of whom have been with him for a long time, so while they may move among his various shows, MacFarlane’s writer-producers rarely leave. For example, Callaghan was a member of the original writing staff of Family Guy. He was named executive producer and co-showrunner in 2009. After a three-year stint with Callaghan and Mark Hentemann at the helm, another long-time MacFarlane cohort, Rich Appel, was brought in last fall as new showrunner. (He came from MacFarlane’s third Fox series, Family Guy spinoff The Cleveland Show, which he ran.) Callaghan and Hentemann stayed on after the showrunner change, and WME-repped Callaghan is now taking the reins of American Dad, which is in its eighth season.