Margaret Qualley as Pussycat
Pussycat does play a vital role in Tarantino’s film, but there wasn’t technically any real Manson follower who went by that name. Her character was inspired by some of the women in Manson’s cult.

Source: Left: Columbia Pictures/ Right: RXSTR
And it’s fair to guess that they drew got the name from Kathryn “Kitty” Lutesinger, who was a notorious member of Manson’s cult. Margaret Qualley, playing the hippie cult follower, really did have to go as-natural and let her armpit hair grow throughout the course of filming.