Alexander Pollock Moore (1867 - 1930) was an American diplomat and editor. He was the publisher of the Pittsburgh Leader when he married the stage actress Lillian Russell, becoming her fourth husband. After she died on June 6, 1922, he served as an ambassador twice: to Spain from 1923 to 1925 and to Peru from 1928 to 1929. As the Ambassador to Peru he played a significant role in negotiating the Tacna-Arica boundary agreement, settling a border dispute between Peru and Chile.