German Bruno Ludke, who killed at least 80 people, mainly women, began his 15-year killing spree in 1928.
Declared
insane, he was sent to a Vienna hospital, where experiments were carried out on him until he died by lethal injection in 1944.
During World War II, Frenchman Marcel Petiot built a sound-proof home in which he killed up to 63 people.
He claimed he was a member of the French Resistance and told his victims, who were mainly Jews and others escaping from the Nazis, that he could arrange for a safe passage out of the country for a fee.
But after receiving the money, he gave them a lethal injection pretending to given them a "vaccination against foreign diseases".
In 1944 police investigated Petiot''s home due to the stench of burnt corpses. He was found guilty and died by the guillotine in 1946.
Fred and Rose West are two of Britain''s most notorious serial
killers. Fred, who hanged himself in Birmingham''s Winson Green prison on New Year''s Day 1995, killed 13 women and girls - including his first wife and two of his daughters - in Gloucester and nearby Much Marcle between 1968 and 1987.
His wife, who is serving a life sentence in London''s Holloway prison, was
convicted of 10 of the murders.
Australia''s two most prolific convicted serial killers are James Miller, who raped and murdered seven women in the 1970s, and Ivan Milat, the notorious "backpack" murderer, who killed seven tourists and buried their bodies in the bush outside Sydney.
But in May this year, Australian police charged three people with murder after finding human remains in a disused bank vault.
Another two were found buried in the garden of an Adelaide house. Police say they suspect the motive for the murders was a welfare fraud.