Young Adult Literature; Science Fiction
Don't be fooled by the book's length; Here Be Monsters! is more young-adult than adult-adult. There are also elements of sci-fi, but we'll get to those in a minute.
As far as YA lit goes, the main character of Here Be Monsters! is Arthur, a kid. We don't know his exact age—and heck, he probably doesn't either, since he was found as a baby and adopted by Grandfather—but since he's learning to find his way in the world and make friends (read: kid problems, not adult problems), we feel pretty safe categorizing this book as YA.
It's also worth mentioning that the author has sprinkled kid-centric warnings and advice throughout the book, like when Willbury tells the boxtrolls: "'I notice that you are rather light on vegetables. You know they are good for you'" (11.70). This less-than-subtle presentation of healthy lifestyle advice is something we're more likely to see in literature aimed at young people.
As far as the sci-fi tag, let's review some of the plot elements of the book:
- A machine that takes the size out of one living being and transfers it to another
- Magnets and engines and stuff
- An underworld pipe/waterworks system maintained by mechanically-oriented monsters
Surely you see our point. Between these plot elements and the fact that one of the main characters, Marjorie, is an inventor, there's enough science in this work of fiction to make it, well, science fiction.