Adolf Hitler caused the murder of many people.
Adolf Hitler . Under Hitler 's leadership and racially motivated ideology , the Nazi regime was responsible for the genocide of at least 5.5 million Jews and millions of other victims whom he and his followers deemed Untermenschen ( `` sub-humans '' ) and socially undesirable . In addition , 29 million soldiers and civilians died as a result of military action in the European Theatre of World War II . The number of civilians killed during the Second World War was unprecedented in warfare , and constitutes the deadliest conflict in human history .