Since it's the holiday season, I gave myself the gift of the author's prerogative to ask Weird Animal Question of the Week: If Krampus, St. Nicholas's demonic counterpart, had reindeer, what would they look like? (Related: "Krampus the Christmas Devil Is Coming to More Towns. So Where's He From?")

My first thought was that "fanged" or "vampire" deer would do nicely as Krampus sidekicks. As it turns out, these shy, small deer probably wouldn't suit the nasty monster at all—but they're fascinating in their own right.

"Fanged deer" is a loose term that refers to male deer with visible canines, including water deer, musk deer, muntjac, and tufted deer.

"The ancestors of all deer were small and had tusks and antlers," said Jen Webb, Zoo Atlanta's carnivore keeper. She is also keeper of the American Zoological Association's muntjac studbook, so she's "responsible for the pedigree, geneology, and geographic history of the species' population" in her area.

During evolution, taller deer species "grew larger antlers and lost the tusks, while smaller deer retained the tusks but kept small antlers," explained Webb.

Keep reading for cool facts about the four fanged deer groups.

View Images A Reeves's muntjac (Muntiacus reevesi) is seen in Warwickshire, England, in 2013. Photograph by Mike Lane, Alamy

Muntjacs

Muntjacs, 12 species of deer native to South Asia, have both antlers and tusks because they maintained various qualities of their ancestors.

Like all fanged deer species, muntjacs are relatively small, shy, and flighty. (See a picture of a Sumatran muntjac caught in a camera trap.)

The animals vary in habitat, geographic location, and several aspects of their appearance and behavior. For instance, the Chinese, or Reeves's, muntjac—one of which lives at Zoo Atlanta—is nicknamed "barking deer" because of its sharp, abbreviated calls. (Watch a video of the animals "barking.")

Musk Deer

A species of fanged deer called the Kashmir musk deer made headlines earlier this year when an animal was spotted in Afghanistan after a 60-year absence, according to an October study in the journal Oryx.

"Musk deer are less well known than other deer because they are secretive, shy, not terribly common, and are found primarily across temperate Asia, from the Himalayas of Afghanistan into southern Russia, which is generally a region of the world that is not well known to the public," said the Wildlife Conservation Society's Peter Zahler, co-author of the Oryx study. (Watch a video of the Siberian musk deer.)

"This is true for other 'fanged' deer as well," Zahler said by email.

All but one of the seven species of musk deer are listed as endangered by the International Union for Conservation of Nature.

The animals are hunted for their musk glands, which are "considered more valuable by weight than gold, fetching as much as $45,000/kilo on the black market," according to the Wildlife Conservation Society.

Tufted Deer

One species of tufted deer, Elaphodus cephalophus, lives in China and Myanmar (Burma) and has very small antlers obscured by tufts of hair—hence its name—but very noticeable tusks.

Zahler said that for small deer that live in thick vegetation, tusks make sense: They're less likely to get tangled in brush than antlers are.

Male fanged deer also use their tusks to fight rival males, and "it may be that visible tusk size is an asset that will cause a rival to back down and avoid a fight," Arnold Cooke, an independent U.K.-based deer researcher, said by email.

Chinese Water Deer

The Chinese water deer is native to China and Korea, but, along with the Reeves's muntjac, has established wild populations in the U.K. after releases and escapes from zoos and parks in the early 20th century, according to the British Deer Society.

The rarest of Britain's six deer species, Chinese water deer are primarily grazers, "and the tusks are, to a degree, hinged in their sockets, and can be held back slightly when the animal is grazing," Cooke said.

The animals also have "ears large and rounded, giving a 'teddy bear' like appearance," according to the British Deer Society.

Sorry, Krampus. Guess you're going to have to find yourself another pet—these "vampires" are just too sweet.

What would make a good companion animal for Krampus? Leave your thoughts in the comments below!