Mark Irby "MRT" Fox (born March 1, 1956) is a retired United States Navy vice admiral who served as the Deputy Commander of United States Central Command (CENTCOM). Prior to assuming his duties at CENTCOM, he served as Deputy Chief of Naval Operations for Operations, Plans, and Strategy (N3/N5), Commander, United States Naval Forces Central Command and Commander, United States Fifth Fleet. He also previously served as the Commander of the Naval Strike and Air Warfare Center at Naval Air Station Fallon, Nevada, and as Communications Division Chief, American Embassy Annex, Baghdad, Iraq.