John Jacob ("Jack" or J.J.) Eller, Jr. (October 15, 1883 – January 20, 1967) was an American track and field athlete, a member of the Irish American Athletic Club and a member of the New York City Police Department from 1905 to 1942.

Eller was a five-time Amateur Athletic Union champion in the 220 yard low hurdles between 1907 and 1912.

"He held the world's record for the 220 yard, 2 foot 6 inch hurdle made at Travers Island in 1908, the time being 24 4/6 seconds and also the 220 yard 3ft.

hurdles made at Celtic Park in October 1908 in 27 and 3/5 seconds."

He also participated in the pentathlon event but quit after three disciplines, with the victory going to Jim Thorpe.