Monstrosities in general, they are very repetitive, and rarely very varied. FO3's deathclaw was just another Veloci-Allosauro-Raptor-ness, at least FO4s deathclaw is slightly more interesting
But - and this goes for movies too - claaaws, faaaangs, wrinkled, broken, gooey, gory skin, guuuurgle, roaaaar, hissss, can we at SOME point move past this? It's not scary anymore.
Also, there are good examples of the opposite, and then people simply don't SEE it
Like, take Game of Thrones - see white-walker fan-art based on book info - these are terrifying, they're shiny, tall, elegant beings - I even thought of the possibility that we're dealing with extraterrestrial conflict (like in Elfquest, if anyone's familiar. The elves there are actually from another planet, crashlanding 10 000 years prior to the comic beginning, and having adapted to the new world, long since losing their high-tech advantages to hunter-gatherer life-styles)
(I'm not saying "the others" are aliens, I'm just saying... with a non-zombie look - I'm thinking non-zombie things about them!)
In the TV series they were immediately given the GORY WRINKLES, CLAAAWS, ROAAAAAR
And to their credit, they're among the most original and freaky looking zombie-monsters, but they STILL are zombie-monsters...
Or "the grudge", or other Japanese horrors - they know how to make things scary, showing a lady, pale, unliving, unbelonging, looking at you. Imagine if you turn around from your computer, and some ghost-chick is standing there, innocent, looking at you, reaching out a hand
You don't NEED velociraptor-claws or gore or fangs or roars
But what did they do in the American remake? GOOORE, DROOOOl, FAAANGS, ROAAAAAR
The gore-wrinkle-monster-approach is less and less scary, every time it's perpetuated.