I tend to use monsters that already exist (legendary or human) when I need to. Rarely monsters impinge upon my writings but in "The Dead Girl and the Wandering tree" a "Dread" comes to the river lands. I like monsters who are flawed as we humans are, weak and hopeless. Lol. How easy is it to kill a vampire? Just wait till morning, wander into the castle crypt with a stake and hammer, Both available cheaply at B&Q or ASDA. Shit, open the curtains. In fact, you can buy a stubby hammer now in Asda (Walmart) so you could just have your vampire extinction kit in your pocket. Not really scary when you think of it. I have rarely attempted an overwhelming evil though I have suggested it often back when writing, "The Crows Feather" and "Trow". Recently I have used "Dread", "Barrow Weights", "Djinn" and humans as the monsters required but I quite like "creature Horror" if it is (almost) believable.
My next couple of books contain no "monsters" apart from in one case, human "monsters" but it has been a feature of my writing for many years. Back to "Tales from this Northern Land" and even then, the monsters were never truly evil. I am done with monsters for the next couple of novels. which will be
in order. "Cold Blue Eyes" then "Under Dark Skies".
To see the monsters again, and there will be many of them, you will have to wait for "The Dark Kind". which will be rife with Monsters of all sorts.