Gregory Laurence Moriarty (born 4 April 1964) is a senior Australian public servant and diplomat, and the current Secretary of the Department of Defence since 4 September 2017. He was previously the Chief of Staff to Prime Minister Malcolm Turnbull. Moriarty has been Australian Ambassador to Iran from 2005 to 2008, Australian Ambassador to Indonesia from 2010 to 2014, the inaugural Commonwealth Counter-Terrorism Coordinator from 2015 to 2016, and the International and National Security Adviser to the Prime Minister.