William Harrington Leahy (October 27, 1904 – May 12, 1986) was a rear admiral in the United States Navy, and the son of William D. Leahy, President Franklin D. Roosevelt's military chief of staff during World War II.

Leahy was born on October 27, 1904, in San Francisco, California.

After attending Sidwell Friends School he completed his undergraduate study at the United States Naval Academy; he also received a master's degree in naval architecture from MIT and did further work in management at Harvard Business School.

[1] Leahy served as Senior Design Officer, Landing Craft Construction, and later Head of the Landing Craft Section, Bureau of Ships, from November 1942 to October 1945 and received Legion of Merit for his service.

[1] He died on May 12, 1986, in Chevy Chase, Maryland, and is buried with Elizabeth and his parents at Arlington National Cemetery.