In The Cabin in the Woods, a group of friends visit the horror movie's eponymous Buckner Cabin for the weekend and unwittingly become part of a ritual human sacrifice. Good girl Dana (Kristen Connolly) is lured into reading several entries aloud from the diary of the deceased Buckner daughter, Patience (Jodelle Ferland), which provides a basic explanation of the Buckner family history; however, the Buckners' true origin is related to the fact that they are instruments of death in an elaborate ritual sacrifice of youth to the so-called Ancient Ones, the gods that used to rule the Earth.
According to Patience's diary, the Buckner family were country folk who lived at the turn of the 20th century and practiced a religion that worships pain, which is why Sitterson (Richard Jenkins) refers to them as "zombified, pain-worshipping backwoods idiots". The Buckners' religion compelled them to torture and to kill those who were unlucky enough to cross their path, and it also seems to have compelled them to ultimately kill each other. Patience's diary is not only a repository of the Buckner family history, but also contains the key to bringing the Buckners back to life. Patience left her diary to be found by a "believer", who, upon reading a Latin inscription therein, would bring the Buckner family back from the grave as zombies so that they could continue their enjoyment of inflicting pain. Dana reads the inscription and inadvertently chooses the Buckners as her group's executioners in the ritual.
In the context of the movie, the Buckner family seems to have been created for the ritual by the Director character (Sigourney Weaver), possibly with the help the Ancient Ones. If true, the Buckner family history may not be real, which would mean that the Buckners are just tools, manufactured along with a stable of other evil creatures, to be used in sacrifices to the Ancient Ones. In one scene, Lin (Amy Acker) describes the Buckners as not being "something from a nightmare", but "something nightmares are from", implying that they and the other creatures were not created, but somehow borrowed. Lin goes on to say that the creatures are "remnants of the old world, courtesy of you know who", pointing downstairs, implying that they were either created or borrowed by "downstairs", i.e., the Director and the Ancient Ones.
In this way, the Buckner family history and their origins are two-fold: first, they were a "zombie redneck torture family" (as described in the office betting pool); and second, they are a tool for use in the Ancient Ones' ritual sacrifice. Both of these backstories for the Buckners can be correct, and they do not cancel each other out. However, it is never explained in the movie if the Buckners were actual people or only created for the purposes of the ritual.
Regardless of their history and origins, the Buckner family is one of the most unique horror movie antagonists, especially in terms of zombies and redneck serial killers. Unlike many zombies, the Buckner family is impossible to kill, which makes them more like supernatural slasher villains Jason Voorhees and Michael Myers than they are like typical zombies. Also unlike most zombies, they do not eat their victims, but torture and kill them with weapons.
They are also very different from similar hillbilly serial killers such as those from The Hills Have Eyes, Just Before Dawn, and House of 1000 Corpses. Unlike most of their fictional redneck relatives, the Buckners can be seen as the heroes of this story. Although the real-life audience is rooting for them to fail in killing Dana and her group, the world in the context of the movie depends on them succeeding. If the Buckner family doesn't complete their task in The Cabin In The Woods, it means the return of the Ancient Ones, who must be satisfied with the sacrifice or they will destroy humanity. Given these crisscrossing and metafictional aspects of their story, the Buckner family occupies a unique place in the horror pantheon, despite whatever their true family history and origins may be.