M. Osman Siddique (born 1950) is an American politician, former ambassador, and author. He served as the United States Ambassador to the Republic of Fiji and to the Republic of Nauru, to the Kingdom of Tonga and to Tuvalu from 1999 to 2001. He was the US Ambassador during the 2000 Fijian coup d'état. Siddique is the first American-Muslim to be appointed as an Ambassador from the United States.