David Jason Muir (born November 8, 1973) is an American journalist and anchor of ABC World News Tonight with David Muir, the news department of the ABC broadcast-television network based in New York City. Muir previously served as the weekend anchor for the flagship ABC News broadcast ABC World News Tonight and co-anchor of the ABC newsmagazine 20/20. Muir formerly acted as principal substitute for World News with Diane Sawyer on weeknights and then succeeded Sawyer in the anchor chair on Monday, September 1, 2014. While at ABC News, David Muir has won multiple Emmy awards and Edward R. Murrow awards for his journalism both overseas and in the United States.