Cliff Booth, the ex-stuntman and current gofer played by Brad Pitt in Once Upon a Time In Hollywood, is one of the most complex movie characters in recent memory.
Keeping in line with Quentin Tarantino's nostalgia-drenched period piece, Cliff represents a breed of male lead we haven't seen on-screen in over a decade. He's a man's man oozing with machismo, ever-composed. He's affable and good-natured with an edge of arrogance, casually racist but somehow still likeable. And yet, there's something cold and dangerous just beneath the surface, a willingness to engage in violence at a moment's notice without ever breaking a sweat. Cliff doesn't come off like a killer, but one gets the sense that he could easily kill.
Partway through the movie, we find out that Cliff might have gotten away with killing his ex-wife—or at least that's the rumor spreading around the Hollywood backlots. While the truth of this rumor is largely irrelevant to the plot, its thematic import might shed light on some of the more dubious elements of Tarantino's vision.
The details of the supposed murder play out through the following context:
While Cliff's best friend/boss Rick Dalton (Leonardo DiCaprio) works on a Western, Cliff is stuck at Rick's house working on the roof. A little bummed out, Cliff reminisces about the last time he booked a gig. Flashback to Rick pleading with a stunt coordinator to give Cliff a shot. The coordinator refuses, citing the fact that he doesn't want to work with a guy who killed his wife. Flashback again (yes, a flashback within a flashback):
Cliff is on a boat with his wife holding a harpoon gun. She's nagging him incessantly, insulting everything about him. That's it. We never see what happens next.
The movie leaves it up to debate whether or not this is even Cliff's memory of what actually happened or the stunt coordinator's reflection of the rumor. The truth is obfuscated even further: As the main flashback continues, Cliff proceeds to best a cartoonish Bruce Lee in a fight. This scene in particular is incredibly problematic for a lot of reasons, but even within the bounds of the narrative, it's hard to say whether or not Cliff's memory is a reliable interpretation of events as they really happened.
Both potential readings make sense. If Cliff really did kill his wife, that fits in line with his character. Even though the story of the murder comes off as a bit of a shock when we first hear about it, Cliff proves his capacity for extreme violence again and again throughout the movie—first when he beats the Manson Family guy who popped his tire and again during the movie's ultra-violent finale. If anything, knowing Cliff killed his wife works as a setup for his violence later on in the movie. Then again, if Cliff killed his wife and everyone knows about it, how did he get away with it scot-free?
Alternatively, if Cliff didn't actually kill his wife, the fact that he still lost his ability to continue getting stunt work speaks to the nature of rumors in Hollywood. Cliff is shown time and time again to be a talented stuntman who can parkour jump onto roofs and take blows with ease. But Hollywood is also an industry notoriously subject to the whims of perception. The idea that a talented person might be unable to get work due to a false story seems culturally prescient, albeit problematic.
Ultimately, both interpretations point to questionable morals at the movie's core. If Cliff didn't kill his wife, Once Upon a Time In Hollywood centers around a talented, capable guy whose career was ruined by a lie involving a woman. That's not exactly the best look considering the current landscape of Hollywood, especially when Tarantino arguably covered for Harvey Weinstein in the past and defended Roman Polanski's rape of a minor. Polanski gets a very kind depiction in this movie, too, all things considered.
But if Cliff did kill his wife, Once Upon a Time In Hollywood suggests that maybe, just maybe, that's kind of okay. After all, Cliff's capability for brutal violence ultimately saves his friends and Sharon Tate from the whims of the Manson Family. Every other instance of Cliff's violence is righteous and, at least within the moral framework of the film, "good." So if Cliff killed his wife, she probably deserved it—at least that's what Once Upon a Time In Hollywood seems to say.
In the end, it's impossible to know whether or not Cliff actually killed his wife, so it's probably best to pick the interpretation with the least troubling implications for you. Then again, which is the lesser of two evils?