Leo C. "Jack" Kiefer (January 1, 1940 – September 24, 1999)[1] was an American professional golfer who won two Senior PGA Tour events in the 1990s.

Kiefer spent his regular career years working as a club and teaching pro.

He played in a small number of PGA Tour events.

Through Monday qualifying and sponsor's exemptions, Kiefer played in enough events in 1992 to finish 32nd on the money list earning him a full-time spot on the Tour in 1993.

Kiefer owed the Champions Tour record for consecutive holes at par or better (97), until it was broken by Morris Hatalsky in 2003.