This study of memoirs by nearly two dozen 20th century individuals involved in the perpetration and commission of mass atrocities examines their strategies of self-representation. Perpetrator lifewriting, from the Holocaust to Khmer Rouge to Abu Ghraib, moves between exculpation and inculpation, with the perps claiming they were mere 'cogs in the wheel', thus accepting complicity but rarely culpability. It shows how the memoirs construct a post facto self, claiming traumas of their own at what they perpetrated. The Sonderkommando texts, emerging from the 'grey zone' as Primo Levi called it, present the ambiguous perpetrator who, as one sonderkommando put it, 'did the dirty work of the Holocaust'. The study concludes with a reading of memoirs by secretaries and office staff who served the leaders who ordered exterminations and torture.