Sylvestre Augustin Ratanga (born 1945?) is a Gabonese politician and diplomat. He served as Gabon's Ambassador to Germany and was later the Secretary-General of the Gabonese Union for Democracy and Development (UGDD), an opposition party. Abandoning the UGDD, he then served in the government as Minister of Transport and Civil Aviation from January 2009 to October 2009, and he has been Chairman of the Board of the (Société gabonaise de raffinage, SOGARA) since October 2009.