Wilhelm Hermann Pfannenstiel (12 February 1890 – 1 November 1982) was a German physician, member of the Nazi Party from 1933, (NSDAP 2828629), and SS officer from 1934, (SS-Standartenführer, SS-No.

He may also share responsibility with other SS officials in criminal medical experimentations on unwilling and uninformed human beings, mainly Jews prisoners in Dachau concentration camp.

Following the invasion of Poland at the onset of World War II he was in Marburg on leave in 1940 and used as a Hygiene Inspector in Berlin, where his duties included also the inspection of concentration camps in the newly formed General Government.

In the years 1942 and 1943, he attended the extermination camps of Operation Reinhard including Belzec, where he personally witnessed the undressing of women and the gassing of Hungarian Jews in August 1942.

The deposition of Wilhelm Pfannenstiel before the Darmstadt Court on 6 June 1950 reads: While the Jews were being taken in, the rooms were lit up with electric light and everything passed off peacefully.

SS-Hauptsturmfuehrer (captain) Sigmund Rascher, a doctor convicted of committing war crimes at Dachau, wrote to him about previous correspondence they had concerning using prisoners as human guinea pigs.

If so, I would devotedly request you to apply to the Reich Research Council and Chief of the business managing board Standartenführer SS Wolfram Sievers .... so that a mobile low pressure chamber may be obtained through the Luftwaffe for your and my joint experiments... — Sigmund Rascher.