Manson died of natural causes at a Kern County hospital according to the California Department of Corrections and Rehabilitation. No further details were given about the circumstances surrounding his death.
He had been serving a life sentence at the nearby Corcoran State Prison for ordering the murders of nine people, including actress Sharon Tate, who was pregnant at the time.
Who was he?
Born Charles Milles Maddox on 12 November, 1934, in Cincinnati to a 16-year-old girl, Manson spent much of his youth shuttled between relatives and juvenile detention halls. By age 13, he had been convicted of armed robbery.
In the 1960s, the charismatic, guru-like Manson surrounded himself with runaways and other lost souls and then sent his disciples to butcher some of LA's rich and famous in what prosecutors said was a bid to trigger a race war — an idea he got from a twisted reading of the Beatles song "Helter Skelter."
The slayings horrified the world and, together with the deadly violence that erupted later in 1969 during a Rolling Stones concert at California's Altamont Speedway, exposed the dangerous, drugged-out underside of the counterculture movement and seemed to mark the death of the era of peace and love.
Despite the overwhelming evidence against him, Manson maintained during his tumultuous trial in 1970 that he was innocent and that society itself was guilty.
"These children that come at you with knives, they are your children. You taught them; I didn't teach them. I just tried to help them stand up," he said in a courtroom soliloquy.
How did he gain notoriety?
The Manson Family, as his followers were called, slaughtered five of its victims on 9 August, 1969, at Tate's home: the actress, who was 8 months pregnant, coffee heiress Abigail Folger, celebrity hairdresser Jay Sebring, Polish movie director Voityck Frykowski and Steven Parent, a friend of the estate's caretaker. Tate's husband, Rosemary's Baby director Roman Polanski, was out of the country at the time.
The next night, a wealthy grocer and his wife, Leno and Rosemary LaBianca, were stabbed to death in their home across town.
The killers scrawled phrases such as "Pigs" and "Healter Skelter" [sic] in blood at the crime scenes.
Three months later, a Manson follower was jailed on an unrelated charge and told a cellmate about the bloodbath, leading to the cult leader's arrest.
Manson was also later convicted of the slayings of musician Gary Hinman and stuntman Donald "Shorty" Shea.
Why did he carve an "X" into his forehead?
Denied his request to represent himself during his 9-1/2 month trial, Manson showed up in court with an "X" carved into his forehead, and would later alter it into a swastika.
Co-defendants Susan Atkins, Leslie Van Houten and Patricia Krenwinkel cut "X"s in their foreheads, shaved their scalps, sang Manson-written songs and giggled through chilling testimony.
His trial was nearly scuttled when President Richard Nixon said Manson was "guilty, directly or indirectly." Manson grabbed a newspaper and held up the front-page headline for jurors to read: "Manson Guilty, Nixon Declares." Attorneys demanded a mistrial but were turned down.
At one point, Manson tried to leap over the defence table at the judge, snarling: "In the name of Christian justice, someone should cut your head off." The judge began carrying a gun afterward.
How long was he in prison?
After a trial that lasted nearly a year, Manson and three followers — Susan Atkins, Patricia Krenwinkel and Leslie Van Houten — were found guilty of murder and sentenced to death. Another defendant, Charles "Tex" Watson, was convicted later. All were spared execution and given life sentences after the California Supreme Court struck down the death penalty in 1972.
Over the decades, Manson and his followers appeared sporadically at parole hearings, where their bids for freedom were repeatedly rejected. The women suggested they had been rehabilitated, but Manson himself stopped attending after 1997, saying prison had become his home.
What are some of his most chilling quotes?
One of Manson's most chilling quotes comes from an interview in which he was asked to describe himself in one sentence.
Leaping forward in his chair, the cult leader giggled, raised his eyebrows and pulled faces before responding: "Nobody."
After taking a pause for dramatic effect, he continued: "I'm nobody. I'm a tramp, a bum, a hobo. I'm a boxcar and jug o' wine. And a straight razor, if you get too close to me."
After serving a 10-year sentence for check forgery in the 1960s, he was said to have pleaded with authorities not to release him, because he considered prison home.
"My father is the jailhouse. My father is your system," he would later say in a monologue on the witness stand. "I am only what you made me. I am only a reflection of you."
Was he any relation to Marilyn Manson?
Brian Hugh Warner, the musician better known for his controversial stage personality under the name Marilyn Manson, formed his name by juxtaposing two American pop culture icons: Charles Manson and Marilyn Monroe.
Additional reporting by agencies