Long story short, some of the monstresses in fiction are more than a bit sexist in their portrayal of
feminity itself as a symbol of horror. Masculinity is played for horror, but not as often. In psychological and literary analysis these are labeled the “monstrous feminine” and the “monstrous masculine.”
The monstrous feminine
The tropes are monstress as temptress, monstress as womb, monstress as temptress and womb, monstress as bride, and monstress as desirable.
The
monstress as temptress attempts to seduce the hero in order to kill him, such as the succubus. She derives her horror factor from turning what should be attractive (sex with a woman) into something harmful (death by sex). A variation on this is that the monster is not actually a woman or female but merely disguises itself as one (e.g.
Pathfinder's vouivre). The most Freudian example would have to be the
vagina dentata ("toothed vagina"). This motif was traditionally used to warn men not to sleep with strange women, although what constitutes "strange" may have in fact referred to foreigners... so extra points for xenophobia?
The
monstress as womb, like the previous trope, turns something traditionally seen as desirable into something horrible. The monstress is monstrous because she gives birth, typically to horrible monsters. This goes all the way back to the "mother of monsters" that may be found in myths around the world. What is less commonly known is that these monstrous mothers often had equally monstrous husbands in a bizarre example of monstrous gender equality.
This trope is a horror-specific relative of the "
mystical pregnancy" trope, although that trope in particular may be played for hope instead to horror. The birth of Christ and numerous imitations are one such example of a happy pregnancy. Far more often, however, a "happy" mystical pregnancy may be an episodic event that is quickly forgotten and the work completely ignores any emotional fallout to the mother afterwards.
A couple examples of such monsters in role playing game bestiaries include the "dark womb" from the
Creature Collection series (reprinted as "
Chorion hag" in the
Monsters of Porphyra series), which clones other creatures to create slaves; and the
drakainia from
Pathfiner (a misspelling of
Dracaena or "she-dragon"), which adds an additional element of sexual assault by forcibly impregnating prey with her embryos.
On a related note, many monsters that do not derive their horror factor from the monstrous feminine have
unequal gender representation: in many cases, males are assumed to be the default and females are reduced to literal baby factories (if they appear at all).
The
monstress as temptress and womb is the most Freudian trope and as the name implies it combines the previous two. One commentator summed it up as "[w]omen exist just to trap men into having babies who will then destroy their hitherto awesome lives." Too many monsters to count are described as an all-female race that keep men of other races as sex-slaves and food, like a praying mantis or black widow spider without the logical non-evil basis those species have for their behavior. Less commonly these monstresses impregnate their unwitting husbands, who then die as their offspring eat their way out (e.g.
Pathfinder's jorogumo). The nibovian wife, from
Numera, exemplifies this because she initially appears to be a normal woman seeking a husband except that her offspring are actually aliens that attempt to kill their "father" right after being born (an irrational
modus operandi that raises numerous questions and seems pointlessly sadistic on Monte Cook's part).
The
monstress as bride is a very old recurring motif in fairy tales around the world. A happy variation, the "
loathly lady", depicts the hero marrying a hideous hag and being rewarded for it when the hag melts away to reveal a comely maiden. A tragic variation is that the hero marries a beautiful woman then, through his own stupidity, reveals her as a reluctant monster and destroys their previously happy marriage (e.g.
Arabic ghoul,
Japanese snow woman,
Celtic nymph).
The
monstress as desirable is a recent development where the monstress is considered desirable because of her monstrous femininity rather than despite it. The colloqual term for this on the internet is "monstergirl." However, such "positive" depictions can easily objectify women either intentionally (since monstergirls are literally a sexual fetish) or by mistake (if the author genuinely does not realize the implications of their writing).
The thriae (the
Pathfinder monster, not the
Greek nymph) is a "positive" mirror of the monstress that kidnaps men for reproduction. They convince men to become their sex-slaves voluntarily and then keep them as pampered studs for the rest of their lives. An entire caste of thriae dancers exists specifically to give lap dances. This is sexist against
both men and women, reducing them to nothing more than their roles in reproduction and domestic housekeeping.
The sirens (again, the
Pathfinder version) are driven to couple with musicians and commit suicide if their prospective lover spurns or leaves them. This is sexist against woman because it depicts her life as being worthless without a husband to spend it with, and it falls into the tired old cliche of "lifelong soulmates you literally cannot live without."
The monstrous masculine
These tropes have male counterparts, but those are far less common since men have traditionally dominated storytelling for millennia. In the internet age they have massively grown in popularity.
The
monster as tempter is a monster who attempts to seduce innocent maidens in order to despoil their purity and/or eat them. This goes all the way back to the incubus, the male counterpart of the succubus. It is present as the wolf in the fairy tale of
Little Red Riding Hood and the titular villain of
Dracula. Here the threat comes from the danger of rape, a motif traditionally used to discourage women from travelling alone or trying to leave their villages. It still has resonance today due to what the media decries as "rape culture," although what this means is highly variable by which country you live in. In more violent parts of the world rape is not considered a crime, whereas in more equitable parts of the world both women and men may face irrational disbelief when they claim to be victims of rape. Ironically, rape is most likely to be committed by a friend or family member of the victim rather than a stranger as the old stories imply.
The
monster as penis is monstrous because, like the monstress as womb, he takes the innocuous male sexual function and turns it into a symbol of fear. The earliest examples include the father of monsters as the husband of the mother of monsters. This includes the
penis dentatus, a male counterpart to the
vagina dentata. Don't believe me? The
Journal of American Folklore recounts the tale of "The Man with the Toothed Penis". The scifi horror movie
Alien bases its monster on the male genitalia (designed by the late H.R. Giger) and it kills its prey by impregnating them with it killer offspring or by literally impaling them with its toothed tongue or spear-tipped tail (all of these are clear phallic symbols). The horror game
Silent Hill 3 includes a boss monster labeled "Split Worm" which closely resembles a toothed penis and abstractly symbolizes birth.
A positive example of this occurs in the surreal artsy indie game
The Void (aka
Tension,
Turgor), which may be analyzed as an allegory for sex and conception. To the writers' credit, it may be interpreted as an allegory for the creative process and for feminism.
The
monster as tempter and penis is possibly the single most misogynistic trope out of all these. Oddly enough it seems to be mostly modern as far as I can tell, being a particularly violent manifestation of the oft-maligned "mystical pregnancy" trope. It is exemplified in the B-movie
Species 2. The titular monster rapes his female victims and they die giving birth to his monstrous offspring. You cannot be more on the nose than that, I suppose.
An example of this in a role playing context is
the minotaur.
The
monster as bridegroom is typically a simple gender flip of the loathly lady motif. A beautiful prince is trapped in the form of a hideous monster and only the princess can save him with true love. This is exemplified in tales such as "
Beauty and the Beast" and "The Frog Prince".
The
monster as desirable depicts the monster as desirable because of his monstrous masculinity rather than despite it. Like its female counterpart, this trope has taken off only within the last century or so and mostly in romance novels. Traditional monsters and other non-human creatures like vampires, werewolves, demons, dinosaurs, centaurs, dark elves and so forth are typical choices in such fiction. This has a substantial LGBT following as well. Colloquial terms include "monsterboy", "monster boyfriend", and "you sexy beast".