"I am the night."
- – Batman
If you go way back into mythology, werewolves and vampires were often connected. So, of course Dungeons & Dragons decided to exploit this by creating a creature with traits of both: enter the Werebat, a therianthrope with a taste for blood and the ability to become a giant bat!
Werebats originated in the Demiplane of Dread, because Ravenloft is crawling with so many vampires and therianthropes that it needed a creature that combined traits of the two. They originated in the adventure "The Baron's Eyrie" in Dungeon Magazine #58, before making their way into official stats in the Ravenloft Monstrous Compendium Appendix I, and from there to the Monstrous Manual in Advanced Dungeons & Dragons. They also got a werebat Darklord named Captain Monette in the splatbook simply titled "Darklords". Strangely, in Dungeons & Dragons 3rd Edition, in a spectacular display of an editing cock-up, though the Werebat's ability score adjustments and bonus feats would be listed in the Ravenloft Monster Manual equivalent, "Denizens of Darkness", the actual monster stat block would be completely missing! And even worse, they'd carry this same error over to "Denizens of Dread", the 3.5 updated version of the manual!
Dungeons & Dragons 3rd Edition also saw the reveal that werebats can be found in the Forgotten Realms, with the splatbook "Monsters of Faerun" providing stats for them. This would lead to the creature returning in Dungeons & Dragons 5th Edition in the adventure "Waterdeep: Dungeon of the Mad Mage.
Despite all this, werebats are not restricted to D&D. Pathfinder states that they are native to Golarion as well, with them debuting in the adventure "Broken Moon", part of the Carrion Crown Adventure Path. They wouldn't formally get written up until the Pathfinder Bestiary 4.
As Ravenloft is the D&D setting of all things spooky, it was only natural to include a variety of were-creatures into the mix,one of which is the Were-Bat. Like other Were-beasts, Were-bats operate on a true and "infected" type of ranking, true were-bats have three forms, consisting of the more stealth oriented human form, though this does have batty features like a upturned nose and long ears, as well as a general aversion to light, and the craving of raw meat and blood.
The second form is that of a stereotypical vampire bat, flying about
biting and sucking *SCRAPING AND LICKING*, scraping and licking blood from helpless victims. The final form is a powerful and feral combination of man and bat, more than capable of ripping a grown man in twain. Infected were-bats have only the option of being either human or one of the other two usually human to hybrid, but some unfortunate ones can only go from human to bat.
Very little information about werebats is actually presented in 3e's Monsters of Faerun... in fact, just three sentences of fluff are interspersed in all the crunch, quoted below:
3e's "Lost Empires of Faerun" simply repeats what Monsters of Faerun said.
The 5e version presented in Dungeon of the Mad Mage is not much better, frankly, with a single small paragraph of fluff - but then, this is standard for 5e therianthropes. This version stats that most werebats are infected goblins, and that goblin society shuns them and pushes them to their periphery due to their voracious appetites; 5e werebats need 1 pint of blood per night to stay strong and healthy.
In Dragon Magazine #266, the article "Dragon's Bestiary: Giant Lycanthropes" revealed that voadkyn, or "Wood Giants", are one of the only two species of giant with a true lycanthrope subspecies. This is the Shadkyn; a voadkyn version of the werebat. Shadkyns resemble pale and skinny voadkyns when in their giant form, but have the ability to become mobats (Huge sized carnivorous bats) or a monstrous voadkyn/bat hybrid, resembling a smoky-colored voadkyn with bat-like ears, vampire fangs, bat wings for arms, and prehensile claws for feet. 75% of infected shadkyns only have access to one of the non-giant alternative forms. Shadkyns can infect both humanoids and other voadkyn with their bite; a non-voadkyn becomes a normal werebat with the shadkyn's smoky coloration.
Ability-wise, shadkyns are basically identical to AD&D werebats, just bigger, stronger and tougher.
Shadkyns live in tribal groups, occupying a similar niche to voadkyns - unlike their non-therianthrope kinsfolk, though, shadkyns are voracious carnivores. Farms within shadkyn territory suffer frequent raids, and a distinct lack of large herd animals such as cattle can be one sign that a traveler has entered shadkyn country. Shadkyn tribes are savage bands, ruled over by the largest and most powerful of their ilk, who reigns with a brutal fist; the tribe lives only to breed and feed, consisting of 1d12+3 males, two females per male, and 2d6 children - the weak or elderly are often cannibalized by the rest of the flock if food is scarce. Tribes frequently (60% chance) keep a flock of 1d10 normal werebats as scouts and servants.
Two factors limit shadkyn numbers. Firstly, only one child is produced per pregnancy - furthermore, 5% of these shadkyn children are born with access to only one alternate form (usually the hybrid) and another 2% can't shapeshift at all, resulting in their being driven from the flock to become bitter recluses. Secondly, shadkyn and voadkyn despise each other, and are constantly warring with one another.
Despite that, the two races can interbreed. The product of such a mating has a 50% chance of being either a shadkyn or a voadkyn, and voadkyn children born to a shadkyn parent have a 50% chance of being "lesser shadkyns" (infected werebat voadkyns).
Fusing the primal thirst of the ravenous bat and the unique abilities of individual humanoids, the werebat is a hybrid creature constituting both bloodlust and cunning. As opposed to vampires, who share some similar abilities with werebats and are often confused with them, these lycanthropic beings are often more savage in their behavior and far less calculating than the shapeshifting undead. As though to prove a point, some werebats go out of their way to take down powerful vampire lords and commandeer the vampires’ higher position—though many also become slaves to such undead after underestimating their prowess.
Natural werebats typically look like normal members of their race, though they often have dark hair, slight frames, severe features, and slightly pointed ears. They typically stand slightly taller than normal for their race, but weigh significantly less.
Ecology: Werebats exalt in the freedom of flight and delight in the taste of flesh. Whereas some lycanthropes try to maintain some sense of humanity while living with their condition, werebats are less inclined to do so and tend to abuse their powers. Their hunger for blood and the chaos often resulting from such impulsions tend to make wholesome living difficult for werebats, and so most simply give in to their bestial natures.
Those who wish for a less gruesome and more respectable lifestyle are in constant struggle with forces both internal and external to themselves. Natural werebats can control their primal urges, but are subject to the corrupting atmosphere that is werebat society, always under pressure to submit to the influence of a werebat master. Afflicted werebats have it far worse, their bodies in constant conflict with themselves in addition to the external forces urging them to give in.
One of the most telltale signs of a werebat is blindness—about half of natural werebats are born with poor vision and need strong spectacles, and some are even completely blind. They make up for this deficiency with other heightened senses, however, and possess sharp hearing as well as strong senses of taste and smell. In cultures where it does not behoove one to have a lycanthropic background, werebats with poor vision tend to simply go without glasses, as their keen ears are more than able to compensate.
Of course, the most obvious sign of werebat lycanthropy appears beneath the full moon, when an afflicted werebat cannot help but transform into its bestial shape. Werebats in animal form are far more savage looking than average bats, and resemble their dire cousins to a greater extent.
Habitat & Society: Werebats possess a pack mentality akin to their bestial kin’s, and are able to fly in large, coordinated packs and execute complex maneuvers easily and agilely. This instinctual group dynamic manifests itself in both lycanthropic and humanoid form, the surrounding society reflecting this pack mentality in legal as well as civil configuration. Entire packs of werebats often live in close proximity to one another, and sometimes even entire towns fall to the power of the winged lycanthropes.
Almost always serving a higher master and subscribing to an unspoken understanding of “one for all,” werebats place great importance on meetings and gatherings, holding such events at barren locations such as caves and abandoned castles where the horde will be undisturbed. These gatherings are largely ornamental in purpose and merely provide the afflicted individuals with some sense of unity rather than being a means to any constructive end. Nevertheless, it is a great taboo in werebat culture to show any disrespect toward collaborative efforts or to each other during assemblies, and any infighting is met with harsh punishment.
Turning an individual into a werebat is not ritualistic or organized by any means, unlike other facets of werebat culture. Werebats themselves feel indifferent about transforming unaffected individuals into afflicted werebats; the disease is spread more often because a werebat doesn’t have enough time to finish slaying her victim before she is caught mid-act or her prey has otherwise escaped her, carrying a cursed scratch as a memento of the occasion. Only later does the individual realize what has happened, and usually too late. In paranoid societies, the horror upon realizing one’s own transformation is usually matched with self-loathing and sometimes even drastic measures such as suicide—for in certain regions werebat-hate is so strong that it is easier to simply end it oneself than face the imminent and almost always malicious persecution of one’s peers.
Old World of Darkness
In Werewolf: The Apocalypse, werebats, or camazotz, are one of the extinct Changing Breeds that the Garous tried to wipe out during the War of Rage.
They were originally Gaia's messengers, carrying knowledge through the Deep Umbra and coordinating among the Breeds. Their patron, Bat, was particularly close to and loving towards his children. Their role as messengers made them very good at running away and navigating hidden places without being caught, which unfortunately just meant that it took more than one horrible genocide to completely destroy them.
Their near-extermination during the War of Rage, which did extinguish all European camazotz, cracked Bat's mind, spawning two personalities; one devoted to Gaia, the other to vengeance and the Wyrm. Most of the survivors of the War of Rage were later hunted down by the Black Spiral Dancers, and then all of those survivors fled to South America, where Shadow Lord conquistadors mistook them for Tzimisce vampires, given their bat-like warforms and blood magic Bat taught them, and killed them off completely.
After that, Bat went completely himshit and his Gaian aspect was wholly subsumed as he gave himself over totally to the Wyrm. To their credit, the Shadow Lords eventually realized the utterness of their fuckup, and the descendant of the hunter who slew the last camazotz has devoted himself to undoing his ancestor's mistake, in recent times even freeing an aspect of Bat from the Wyrm's grip. And there are rumors that a few camazotz survived even this out in the deepest depths of the Deep Umbra, occasionally dropping off information at old dead-drops to aid the other Gaians, though if so, they've understandably had enough of this shit and never show themselves to any other Gaians under any circumstances and no expedition to locate them has ever succeeded.
They reproduced like the corax, binding a spirit to a human child via a complex ritual that could fail at many stages, further limiting their ability to survive and making them vulnerable to population devastation. Also like the corax, they had no metis; the ritual automatically failed if attempted for the child of two camazotz.