Sir Mark Justin Lyall Grant is a distinguished former senior British diplomat and government official. He served as the United Kingdom's National Security Adviser from 2015 to 2017 and as the Permanent Representative of the United Kingdom to the United Nations from 2009 to 2015. During his tenure at the UN, he held the office of President of the United Nations Security Council four times.
His extensive career within the Foreign and Commonwealth Office (FCO) began in 1980.