Monster theory is, in general, an attempt to investigate the human fascination with the other, and why this other is expressed as monstrous (Mittman viii). Monster theory has come into its own as a discipline in the last decade, though its roots are much older. Mittman identifies the first text in modern monster theory as Tolkien’s Beowulf: The Monsters and the Critics (Mittman xi). Tolkien pushed back against the then-current notion that Beowulf could only be taken seriously as either a historical document or an epic if excised of its dragons. Tolkien accused his contemporaries of being embarrassed of the “fairy story” elements of Beowulf to the point of ignoring the fundamental structural aspects of the poem. He argued, in fact, that the dragons – including Grendel – were the operative characters in the poem. The hero is tested against the monsters, and through defeating them earns his status as hero (Tolkien x). Tolkien’s basic thesis of the functional monster carries down into monster studies eight decades later. Monsters are, in a sense, nothing to fear.

So what is a monster?  Glony, Cohen, Murgatroyd and others begin at etymology and the Latin root word monstrum. In its earliest usage, monstrum was any omen sent by the gods (Murgatroyd 1). Saint Augustine, writing sixteen hundred years before Murgatroyd, connected monstra to the verb monstrare, “to show,” and called monsters lessons sent from God (Augustine CD 18). “Monstrous” in English has an implicit meaning of either physically horrifying or morally evil, but these definitions are too narrow. Anything otherized can be a monster. Serina Paterson calls monsters “othering agent[s]:” their presence, wherever they are, signals a distance from the norm (Paterson 2011, p. ). The monster does not have to be fully othered to be a monster; it may lurk in society or be out in the forefront. A monster does not always have to be gruesome to act as a monster. Noël Carroll, writing about monsters in horror movies, transcends the need for the hideous monster, preferring to define monstrosity by the strong (and often negative) emotional reaction engendered, which he defines as “art-horror” (Caroll 1990, p. x). He traces the favoring of reaction over the grotesque body to Mary Shelley and Frankenstein. Glony also identifies Shelley as a sea-change moment in the consideration of monsters (Glony x) However, medieval theologians were wrestling with the definition of the monster far before Shelley. Christ could be understood as a monster, not because of the grotesque mutilations inflicted on His body during the Crucifixion, but because of His inhuman, impossible transcendence of the physical form (Mills).  Cohen argues that the monster is inherently attractive, even erotically so (Cohen x). Bakhtin, writing fifty years before, located monsters in a carnival atmosphere, their exaggerated forms comic and not demanding of the automatic negative reaction favored by Carroll and other horror theorists. What defines a monster is not gruesomeness, but its function within a given folktale, passage, or society.

A monster is also a transgressive creature. Hybridization runs through the study of monsters in western thought from ancient Greece to the present day. Aristotle, when defining monsters, argues that the essence of a monster is its straddling of two forms, and thus its impossibility. Augustine calls the Roman god Janus a monster specifically because of his two faces.  (couple sentences on hybridization from Cohen + Mittman). By virtue of being both human and animal, the animal bride is a hybrid both literally and ontologically.

In his influential work Seven Theses On Monster Culture, Jeffrey Jerome Cohen positions monsters as a method for reading culture. Since monsters illustrate the fears and boundaries inherent in a society, their transgressional nature shows quite clearly where the acceptable ends (Cohen 3). Cohen’s seven theses of monster culture have been the most helpful in exploring the role of animal wives in the North Atlantic. They are as follows:

1.	The monster's body is a cultural body.

That is, upon the monster’s physical body is inscribed the culture from with it is birthed. Cohen insists on a purity of function, derived from the etymology of monster – “the monster exists only to be read,” as he puts it (Cohen 4).

2.	The monster always escapes.

This thesis is core to the animal bride story, to ATU 402, and to related ATU tale types. Sometimes the escape happens when the husband breaks a taboo. Sometimes the child of the animal bride gives her the key to her escape (LaFontana). Sometimes the animal bride writes her own deliverance by finding the sealskin. Sometimes there is a second escape, as when Kópakonan returns to the house where her seal children have been murdered, lays a curse on Kalsoy, and leaves. Contact with the "Familiar" is still possible - besides Kópakonan's return, there are the Orcadian selkies trailing behind their former husbands' boats and Selkona ushering fish towards her human children's catches - but the escape takes the monster out of the liminal space and situates it back in the dichotomous "Other"-realm, letting it either integrate its hybridized nature or dispose of the familiar.

3.	The monster is a harbinger of category crisis.

Cohen claims that the monster resists categorization due to the hybridization – whether literal, in the terms of its strange body, or in terms of its straddling of two worlds. Liz Glony resists this, identifying categorization as one of the methods to deal with monsters. This categorization is not just in terms of theory but in medieval bestiaries and modern children’s games, such as Pokemon and Dungeons and Dragons (Glony 9). However, the question is: once a monster is categorized, what does one learn from that categorization? Glony draws a distinction between categorization and rationalization, making rationalization the domain of cryptozoologists, but this is a false dichotomy. To rationalize a monster is to categorize it as something known, but knowing a monster - or seeming to know it - does not allow for control. A known monster could not escape.

4.	The monster dwells at the gates of difference.

In the animal bride story, the most easily identifiable “gate of difference” is the split between human and animal. Other “gates of difference” are culturally dependent and can only be investigated within the bounds of the culture.

5.	The monster polices the border of possibilities
6.	Fear of the monster is really a kind of desire
7.	The monster stands at the threshold of becoming

Cohen’s first thesis drives all the others. If the monster is a cultural body, then it must be analyzed within its culture. Crisis, difference, possibilities, desire, and becoming are all specific to a culture. Taken together, this places a monster in a permanent liminal space.