High Quality Content by WIKIPEDIA articles! Ivan the Terrible (born c. 1920) is the nickname given to a notorious guard, thought to be Ivan Marchenko, at the Treblinka concentration camp during the Holocaust. The moniker alluded to Ivan IV, also known as Ivan the Terrible, the murderous and psychopathic Tsar of Russia. "Ivan the Terrible" gained international recognition from the 1986 John Demjanjuk case; however very little is known about Ivan Marchenko, and he is not mentioned in any early authoritative Holocaust literature. John Demjanjuk was accused first of being Ivan the Terrible at the Treblinka concentration camp, but in 2011 he was convicted of war crimes as a different guard named Ivan Demjanjuk at the Sobibor extermination camp.