Victor Todd has been jailed for 18 years after he preyed on two teenagers and two young boys during a 14 year period of offending.
Todd, Jubliee Street, Morley, was handed an extended prison sentence after a court heard how he deliberately preyed on vulnerable victims between 1971 and 1985.
The 77-year-old had already served two prison sentences in the 1960s for serious sex offences against youngsters when he targeted his victims.
Jurors at Leeds Crown Court heard Todd's offences included raping a young mum at his flat.
He subjected a 17-year-old male to a serious sex assault.
Todd then threatened the same victim with a knife before subjecting him to a similar sex attack after he reported the initial assault.
Todd was found guilty of rape, five serious sexual offences and three offences of indecent assault after a trial in December.
Geraldine Kelly, prosecuting, said his victims all suffer with mental health issues as a result of the abuse.
She also said one of the children tried to take his own life at just nine years old.
Timothy Jacobs, mitigating, said Todd would find coping in prison difficult due to his age and failing health.
Recorder Patrick Palmer told Todd: "You still deny these offences.
"You have shown no remorse for your offending and that I find was supported by your demeanour in the course of the trial."Todd must serve a custodial term of 18 years, two thirds of which must be spent in custody.
He must then serve a further one-year period on licence.
He was told he must go on the sex offenders register indefinitely.
Members of Todd's family, who say he is now a 'shell of the man he used to be', sat in the public gallery throughout the trial and the sentencing.