Keith Alexander Hessler
- Bats Left, Throws Left
- Height 6' 4", Weight 2015 lb.
- School Coastal Carolina University
- High School Springbrook High School
- Debut August 8, 2015
- Final Game September 30, 2016
- Born March 15, 1989 in Washington, DC USA
Keith Hessler was called up from the minor leagues by the Arizona Diamondbacks on August 8, 2015 to take the place of Oliver Pérez, a veteran lefthanded reliever who had been traded earlier in the day. He made his debut that same day, pitching a perfect inning of relief and striking out a pair of opponents in a 4-1 loss to the Cincinnati Reds. He pitched a total of 35 major league games for the D-Backs in 2015 and 2016 and the San Diego Padres in 2016, going 1-1, 5.56. He was claimed off waivers by the Padres on May 10, 2016.