Sharon Marie Tate Polanski (January 24, 1943 August 9, 1969) was an American actress and model. During the 1960s, she played small television roles before appearing in films and was regularly featured in fashion magazines as a model and cover girl. After receiving positive reviews for her comedic and dramatic acting performances, Tate was hailed as one of Hollywood's most promising newcomers.

She made her film debut in 1961 as an extra in Barabbas with Anthony Quinn. She next appeared in the horror film Eye of the Devil (1966). Her most remembered performance was as Jennifer North in the 1967 cult classic film Valley of the Dolls, which earned her a Golden Globe Award nomination. That year, she also performed in the film The Fearless Vampire Killers, directed by her future husband Roman Polanski. Tate's last completed film, 12+1, was released posthumously in 1969.On August 9, 1969, Tate and four others were murdered by members of the Manson Family, a cult, in the home she shared with Polanski. She was eight-and-a-half months pregnant.

Charles Milles Manson (né Maddox; November 12, 1934 – November 19, 2017) was an American criminal who led the Manson Family, a cult based in California, in the late 1960s. Some of the members committed a series of nine murders at four locations in July and August 1969. In 1971, Manson was convicted of first-degree murder and conspiracy to commit murder for the deaths of seven people, including the film actress Sharon Tate. The prosecution contended that, while Manson never directly ordered the murders, his ideology constituted an overt act of conspiracy.Before the murders, Manson had spent more than half of his life in correctional institutions. While gathering his cult following, Manson was a singer-songwriter on the fringe of the Los Angeles music industry, chiefly through a chance association with Dennis Wilson of the Beach Boys, who introduced Manson to record producer Terry Melcher. In 1968, the Beach Boys recorded Manson's song "Cease to Exist", renamed "Never Learn Not to Love" as a single B-side, but without a credit to Manson. Afterward, Manson attempted to secure a record contract through Melcher, but was unsuccessful.

Manson would often talk about the Beatles, including their eponymous 1968 album. According to Los Angeles County District Attorney, Vincent Bugliosi, Manson felt guided by his interpretation of the Beatles' lyrics and adopted the term "Helter Skelter" to describe an impending apocalyptic race war. During his trial, Bugliosi argued that Manson had intended to start a race war, although Manson and others disputed this. Contemporary interviews and trial witness testimony insisted that the Tate–LaBianca murders were copycat crimes intended to exonerate Manson's friend Bobby Beausoleil. Manson himself denied having instructed anyone to murder anyone.

Manson's notoriety as an emblem of insanity, violence, and the macabre influenced pop culture. Recordings of songs written and performed by Manson were released commercially, starting with Lie: The Love and Terror Cult (1970). Since his incarceration, various musicians have covered some of his songs. Although originally sentenced to death in 1971, his sentence was commuted to life with the possibility of parole after the California Supreme Court invalidated the state's death penalty statute in 1972. He served his life sentence at the California State Prison, Corcoran, and died at age 83 in late 2017.