Laszlo Csatary was accused of sending nearly 16,000 Jews to death camps and beating prisoners in an internment camp he ran during the war.
Csatary died in a hospital at the age of 98. His attorney told reporters "he had been treated for medical issues for some time but contracted pneumonia, from which he died."
Csatary always claimed he was only a go-between for his country Hungary and the Germans who operated the death camps.
Csatary escaped after the war and became an art dealer in Canada.
Prosecutors disagreed claiming Csatary "deliberately provided help to the unlawful executions and torture committed against Jews."
The nation revoked his citizenship in 1997 and he fled the country and disappeared.
He was found in Hungary last year and jailed.
The head of the Simon Wiesenthal Center says of his death “it is a shame that Csatary, a totally unrepentant Holocaust perpetrator who was finally indicted in his homeland for his crimes, ultimately eluded justice and punishment at the very last minute.”