David Jason Muir (/ˈmjʊər/ MURE; born November 8, 1973) is an American journalist and anchor for ABC World News Tonight and co-anchor of the ABC News magazine 20/20, part of the news department of the ABC broadcast-television network, based in New York City. Muir previously served as the weekend anchor and primary substitute anchor on ABC's World News Tonight with Diane Sawyer before succeeding her on September 1, 2014.