A lot of our stereotypical fantasy races/creatures come from European mythology and folklore, particularly Greek, English, and Norse: elves, dwarfs, centaurs, demons, fairies, etc. So, logically, one of the simplest ways to change up the fantasy we write is to bring in creatures from other cultures. Here are some resources to help you get started:
A lot of the creatures on this list are common in fantasy, but there are a few I hadn't heard of before.
This author provides links (when possible) to multiple sources of information.
This author has quite a few books about mythologies and history from various cultures. I just started his combined book on Greek, Norse, and Egyptian mythology (free when you sign up for his email list).
The Rick Riordan Presents imprint has published multiple new series that incorporate Hindu, Maya, Korean, Cuban, Mexican, Navajo, African, African-American, and Mesopotamian folklore (not all in the same books, of course!).
This book of Japanese folktales was a fixture in our family library when I was little, though I was too young to understand most of the stories then.
I don't usually recommend Wikipedia for research, but I'm less rigid about that when it comes to mythology. This page lists mythological creatures by type, and this page links to all sorts of Wikipedia articles about mythology.
One of my WIPs is an accidental-time-travel screenplay involving a villainous kitsune, but I definitely want to do something with selkies at some point. What non-stereotypical creatures would you like to bring into your fantasy? Use the social-media links at the top of this page to join the discussion!