Friedrich Hartjenstein (3 July 1905 – 20 October 1954) was a German SS functionary and war criminal.

A member of the SS-Totenkopfverbände, he served at various Nazi concentration camps such as Auschwitz and Sachsenhausen.

Hartjenstein was arrested by the British and, on 6 June 1946, was sentenced to life imprisonment at Wuppertal for executing four female agents of the British clandestine Special Operations Executive organization.

Hartjenstein was extradited to France, where he was tried for his crimes at Natzweiler, and received another death sentence.

He died of a heart attack on 20 October 1954, aged 49, while awaiting execution in Paris.