Call it “ologyology”: the study of the proliferation of children’s books with titles referencing the study of the supernatural. Candlewick’s perennially popular Ologies series is perhaps the most prominent example, but this fall will see the arrival of several “ology” titles that are similar to the Candlewick series in name only (unlike those interactive books, these are novels and a picture book). Two of them—The Monstrumologist and The Monsterologist—have nearly identical titles, but very different ways of addressing their ghoulish subject matter.

The Monstrumologist (S&S, Sept.) by Rick Yancey, author of the Alfred Kropp series, is by far the darker of the pair. The young adult novel, which purports to be the journal of a young assistant to a monster-hunting doctor in late 19th-century America, involves the discovery of a group of headless “anthropophagi” with a taste for human flesh. (The monsters, which have sharklike mouths in their chests, aren’t Yancey’s creation: Herodotus, Shakespeare and others have referenced them in their writing.)

Billed as a “memoir in rhyme,” the picture book—style The Monsterologist by Bobbi Katz, illustrated by Adam McCauley (Sterling, Sept.), is comparatively lighthearted in its approach to things that go bump in the night—though not without some grisly moments of its own. The eclectic collection of poems includes a missive from Dracula, an academic survey for zombies and Grendel’s recipe for Danish Pastry (“Take half a dozen dozing Danes. Split their skulls”), set against collagelike illustrations that feature “photographs,” personal ads, emails, stamps and letters.

Both books were preceded, in name and in pub season, by Candlewick’s Monsterology: The Complete Book of Monstrous Creatures, which came out last year. This September, Candlewick will release TheMonsterology Handbook: A Practical Course in Monsters, a gifty companion book for monsterologists-in-training that provides background information about beasts of sea, sky and land, as well as some troubleshooting tips (“Remember which head eats what food when it is time to feed the chimera”).

“The big thing the Ologies did is they introduced reference material in a fun way to kids so it’s not like reading the dictionary,” says Heather Doss, children’s buyer at book wholesaler Bookazine. Doss says the Ologies are still strong sellers, adding that the three latest titles, Monsterology, Oceanology and Spyology, “upped the ante” in terms of their design and novelty elements.

Also for fall, on the friendlier end of the “ologist” spectrum, is Nathaniel Fludd, Beastologist: Flight of the Phoenix by R.L. LaFevers, illustrated by Kelly Murphy (Houghton Mifflin, Sept.). Targeting a middle-grade audience, this first book in a planned series follows Nathaniel as he is trained to study exotic/mythical creatures by a distant cousin.

Doss says that the monster market has been “pretty targeted” lately, citing the familiar vampire, zombie and werewolf crazes. But she believes that “general” monster books are just as sure a bet. “Monsters are always going to be a good source of entertainment, especially for middle-grade kids,” she says. “They’re at the age where monsters are still scary, but they’re learning they don’t have to be quite so scary—and that sometimes being scared is fun.”