Robert Swan Mueller III (/ˈmʌlər/; born August 7, 1944) is an American lawyer and civil servant. He was the sixth Director of the Federal Bureau of Investigation from 2001 to 2013. He is a Republican. He was appointed by President George W. Bush and his original ten-year term was given a two-year extension by President Barack Obama.

Mueller is the longest-serving FBI director since J. Edgar Hoover. He is currently head of the Special Counsel investigation of Russian interference in the 2016 United States elections.