In 10 Cloverfield Lane (2016) by Dan Trachtenberg, Howard (John Goodman) is presented as the film's villain; however, there is a theory that Emmett (John Gallagher Jr.) is the real villain. At first glance, the theory is compelling, but it ultimately fails to solve the mystery that it addresses, because it relies on assumptions and information external to what has been captured on film. In other words: it is pure speculation.
A theory posted on Reddit states that Emmett killed the girl seen in Howard's photos, which would make him the real villain. Howard told Michelle that the photos are of his daughter, Megan, but Emmett claims the girl is Brittany, a former classmate of his little sister; he claims the girl went missing a couple of years before the film's catastrophic events. The theory states that Emmett lies about the photos to hide his guilt and frame Howard, but this makes no sense, since Michelle was already accusing Howard.
Either Emmett or Howard is lying, that much is certain. However, regardless of who the girl is, the theory presents very weak evidence that she was kidnapped or murdered at all. The only evidence presented is an earring worn by the girl in the photos and the word help scratched into the window of the air filtration control room. The earring could have been left by the girl at any time and for any reason, and Howard himself might have left it there. The word help could also have been scratched into the glass by anyone—including Howard, though that seems unlikely, given his extremely self-sufficient ways.
Mistrust And Paranoia Are The Real Villains In 10 Cloverfield Lane
Michelle assumes that Howard murdered the girl based on weak evidence, and the theory uses the same flimsy evidence to accuse Emmett of the crime. The truth is that the girl—whoever she is and whatever her relationship to Howard may be—could be alive and well fighting aliens, or whatever is attacking the country, in Houston or elsewhere. Other details in certain versions of this theory also don't hold water.
A version of the theory posted on Vocal states that it must have been Emmett who killed the girl because Howard would never be able fit through the air shaft to access the room where the girl was allegedly murdered; this is simply false, since Howard could have entered the room via the access hatch that was blocked—incidentally, the film never reveals what was blocking the hatch. This version of the theory also states that it was Emmett who ran Michelle's car off the road, but this is unlikely because Howard admitted to doing it by accident.
All three of the film's main characters are flawed humans in very different ways, and any theory can depict any one of them in a light that makes them out to be the villain. However, the real villains of 10 Cloverfield Lane are mistrust and paranoia—these are the common enemies in films where people are forced to live in close quarters with limited supplies due to any type of apocalyptic scenario, such as in The Divide and in 400 Days. By the film's ending, the audience is left to wonder what might have become of the seemingly doomed trio if they had all been a bit more honest with each other.