Miklós Nyiszli (17 June 1901, Szilágysomlyó, Austria-Hungary – 5 May 1956, Oradea, Romania) was a Jewish prisoner at the Auschwitz concentration camp.
Nyiszli, his wife, and young daughter, were transported to Auschwitz in June 1944.
Upon his arrival, Nyiszli volunteered as a doctor and was sent to work at number 12 barracks where he operated on and tried to help the ill with only the most basic medical supplies and tools.
He was under the supervision of Josef Mengele, an SS officer, physician and war criminal.
Mengele decided after observing Nyiszli's skills to move him to a specially built autopsy and operating theatre.
The room had been built inside Crematorium II (Crematorium I was in Auschwitz Town camp), and Nyiszli, along with members of the 12th Sonderkommando, was housed there.