Alfred John Lill Jr. (January 1, 1880 - March 18, 1956) was the president of the Amateur Athletic Union and a member of the United States Olympic Committee for the 1936 Summer Olympics in Berlin, Germany.

[1][2] He was born on January 1, 1880, to Alfred John Lill Sr. in Boston, Massachusetts.

In 1913 he was elected president of the Amateur Athletic Union running against George Franklin Pawling.

He and Governor George Howard Earle III of Pennsylvania and Mayor Fiorello La Guardia of New York City proposed an Olympic boycott.

He died on March 19, 1956, at the Somerset Hospital in Somerville, New Jersey.