William Manning Rountree, Jr. (March 28, 1917 – November 3, 1995) was an American diplomat. He was born in Swainsboro, Georgia to William Manning Rountree, Sr. and Clyde Branan Rountree on March 28, 1917. William Sr. died when his son, the youngest in a family of seven children, was eighteen months old. The family moved to Atlanta when William Jr. was six, where he attended high school. After graduating from high school in 1935, Rountree got a job with the United States Department of the Treasury where he held various clerical and accounting positions. He later became involved with the lend-lease program.