Once Upon a Time in Hollywood is Not a True Story but it …

One aspect of Once Upon a Time in Hollywood that’s loosely based on a true story is the inclusion of Sharon Tate, portrayed by Margot Robbie, and her tragic death at the hands of Charles Manson’s followers. The late actress was stabbed to death by members of the Manson Family in 1969, the year Quentin Tarantino’s movie takes place.

: http://www.historyvshollywood.com/reelfaces/once-upon-a-time-in-hollywood/