Whenever you pick up any type of fantasy book, whether from the ever popular tween section of the bookstore or a classic from the back of your local library, what type of creatures are present in the story? Is it perhaps the ever somehow popular romantic vampire or tragic shape-shifting werewolf? Maybe you have a wicked witch present with her slew of poison apples, some type of wizard from an ancient world, or the mysterious fairy. Perhaps you like the darker material, and have a Demoneta type demon in the book you are glancing at. If you haven't caught on already, then if you have any of these creatures in a fantasy book, you might be experiencing a lack of creature diversity. Although it is not bad to use one or two of these creatures in a story from time to time, the multitude of books currently out with the same fantasy icons is becoming a bit too sour.
The great thing about the fantasy genre is that you have more freedom to choose any type of mythological or supernatural creature of your liking. Sick of reading a werewolf themed book for the thirtieth time? Perhaps you need to read something focused on the Japanese nine tailed vixen, the kitsune. Don't want the brave knight to fight a dragon in your story? A griffin, chimera, or even a silly jackalope could make a suitable replacement. There are so many fantasy creatures to choose from who unlike the more popular figures barely have any individual books focused on them.
I am not saying to completely stop reading Harry Potter, The Vampire Diaries, Blood with Chocolate, or the Demoneta series just because the supernatural creatures used there are very familiar. I just am saying maybe checking out or creating something new once in a while really shows the potential diversity you have in the fantasy genre. That is the fun of these books. Your imagination can go as wild as it wants. Unlike other types of stories, you have the freedom to create any type of imaginative creature your mind can come up with.