Emil Ketterer (6 August 1883 – 23 December 1959) was a German physician and track and field athlete who competed in the 1912 Summer Olympics.

He was the father-in-law of Hanns-Martin Schleyer, an SS officer and West German business executive who was murdered by the Red Army Faction in 1977.

However, at the 1912 Summer Olympics in Stockholm, he was eliminated in the first round of the 100 metres competition when he did not finish his race due to an injury.

Following the Nazi seizure of power, Ketterer was named head of the German Sports Medicine Association.

During his time in the SA medical service, Ketterer was known to be a strong proponent of the euthanasia program that was carried out on disabled persons.

[1] His daughter Waltrude (1916–2008) was the wife of Hanns-Martin Schleyer, who was kidnapped and murdered by Red Army Faction terrorists in 1977.