William Sterling Byrd Lacy (February 5, 1910 – December 11, 1978) was an American diplomat who served as the third United States Ambassador to Korea from May to October 1955. He negotiated a series of cultural exchanges with the Soviet Union, which indirectly created the setting of the Kitchen Debate between Richard Nixon, the Vice President of the United States, and Nikita Khrushchev, the Premier of the Soviet Union.