Kenneth Webster "Jack" Mollenkopf (November 24, 1903 – December 4, 1975) was the head football coach at Purdue University from 1956 until 1969.

On January 2, 1967, Mollenkopf coached the Purdue's first appearance in the Rose Bowl, leading the Boilermakers to a 14–13 victory over USC.

Against Purdue's in-state rivals, Mollenkopf tallied an 11–2–1 record versus Indiana and a 10–4 mark against Notre Dame.

Mollenkopf's inaugural season in 1956 was the only losing campaign of his tenure as head coach at Purdue.

In 1994, Coach Mollenkopf was inducted as a member of the inaugural class of the Purdue Intercollegiate Athletic Hall of Fame.