Warning: This story does include some minor character spoilers.
Quentin Tarantino's ninth feature film, Once Upon A Time In... Hollywood, has quite the colorful (and star-studded) cast of characters. Brad Pitt plays professional stuntman Cliff Booth who is loosely based on a real person. But beyond that, his life has a few prominent question marks, like, just as a super casual example: Did he actually kill his wife?
After years of working together, Booth becomes more than simply TV star Rick Dalton's (Leonardo DiCaprio) stunt double. He becomes his driver, close friend, and inspiring pep talk giver. Other than what he is to Dalton, we don't know too much about Booth's backstory. He is a Vietnam War veteran, he lives in a dilapidated trailer in the Los Angeles suburb of Van Nuys, he's got a very expressive pit bull as a pet.
Booth is purportedly inspired by Burt Reynold's stunt man, Hal Needham; however, their personal backstories other than being stunt men with remarkably close relationships to the stars whom they stunt for have little to no overlap. While Booth's career is slowing down as Dalton has fewer and fewer stunts needing to be done, Needham went on to have a hugely successful career as a director.
Set at the peak of Hollywood's hippy era in the summer of 1969, Once Upon A Time In... Hollywood follows two fictional men, Booth and Dalton as they make the leap from television to film in a world and industry that is changing right before their eyes. As their world changes, the world at large is about to change in the wake of the Manson Family murders, a pivotal moment in history with which Booth and Dalton cross paths.
Unlike many of the real people portrayed alongside Booth and Dalton, both characters are inspired by real people from that time, but are essentially works of fiction. So whether Booth killed his wife isn't something we can delve into the true crime blogs and Reddit forums to find theories and old police documents. All we as the viewers have to go off of is a single flashback in which we see a Booth on a boat with his wife who mercilessly berates him. That doesn't do much to confirm or deny the rumor, but between that and Booth's violent streak when anyone crosses him, it would make sense that your inner true crime enthusiast is a bit suspicious.
The good part about classic Hollywood films is that most of them used to have very neatly resolved endings. Nothing was left unexplained. With Once Upon A Time In... Hollywood, that is not the case. We never actually find out whether Booth killed his wife. We are just lead to believe that he might have which just makes him all that much more mysterious and dangerous.