Charles Manson, the notorious head of a cult which he directed to commit murders, has died in hospital aged 83.
He was admitted to Bakersfield hospital in California earlier this month, US media reported.
In 1969, Manson followers, known as the Manson family, killed seven people.
Among the victims of his killing spree was heavily pregnant Hollywood actress Sharon Tate, the wife of director Roman Polanksi.
Four other people at her home were also brutally stabbed to death. The next day, a wealthy couple in Los Angeles were also killed by the “Manson family”.
The news of Manson’s death was first reported by TMZ magazine, which quoted Tate’s sister, Debra.
She said she had received a phone call from prison officials.
Manson believed in a coming race war in America, after which he could emerge as a leader of a new social order – a vision nicknamed “Helter Skelter”, after a Beatles song Manson became obsessed with.
Prosecutors argued that Manson hoped black Americans would be blamed for the killings, heightening racial tensions.
He convinced a number of his followers that he was the reincarnation of Jesus Christ, using a reported combination of drugs and genuine charisma which brought the “family” – mainly young, middle-class women – under his control.
Manson killed no-one himself. Instead, his followers carried out the murders on his orders.
Nonetheless, he was convicted of the murders and sentenced to death in 1971.
Before that sentence could be carried out, California outlawed the death penalty, and his sentence was changed to life. Over the course of his life in prison, Manson applied for parole 12 times.
At the last, in 2012, the parole board said he had not appeared to have made any efforts to rehabilitate himself.
Nor was he a model prisoner, having been caught in possession of a weapon and contraband mobile phones.
In 2014, he was granted a marriage licence to wed a 26-year-old woman who claimed she loved him, but the licence expired and the marriage did not go ahead.
Since his conviction, Manson and his followers have been the subject of dozens of documentaries and books.