Monsters are a favored subject for kids all year round, not just as Halloween. They often get quite creative with their personal interpretations of what a monster would look like. I invite you to visit "The Monster Project 2015" in which children's monster drawings are redrawn by professional artists and illustrators. It is a real treat!
Carlos Lerma, courtesy The Monster Project 2015.
Share "The Monster Project 2015" with your kids, too, and encourage them to express themselves with paper and crayons, clay, or whatever their favorite medium may be. A child who is not particularly comfortable with his/her drawing skills, may just prefer to look through a series of books called "Fantasy field guides" by Aaron Sautter (all found in the J 398 section). One title is A Field Guide to Dragons, Trolls, and Other Dangerous Monsters [J 398.2454 SAU].
And my favorite monster movie--Monsters, Inc. [J DVD MON], is fun for those kids who find scary monsters a bit too much to take.