Okay, so...I think the
Jurassic Park franchise is a good example of 'scary animals.' The entire series of films is about clever, hungry animals attacking and eating people. Sure, there are plenty of films about killer sharks -
Jaws,
the Meg, all the
Sharknado films. And there's always
Gremlins. But
Jurassic Park is a really good one - it's meant to scare you, and you're meant to believe these are 'real' (albeit prehistoric) animals.
And, easily, hands down, the scariest critter in the park is...the velociraptor. What makes velociraptors so scary?
Number one is their intelligence. They can figure things out. They can open doors. They can manage not to fall for the easy/obvious trap, and plot a counter trap of their own. They don't talk, of course, but they definitely communicate. (raptor
sounds)
Secondly, their design is sleek and with a heavy emphasis on the claws and teeth. They have those giant raptor claws that are really impressive at tearing, both on their hands and feet. They're small enough that they can get into confined spaces; they're not huge monsters like the t-rex. They are right up close and personal. Very powerful, very reptilian, very fast.
Three - they coordinate. They hunt in such a way that you never see the one coming who gets you. So, the visible cat in front of you while the other cat sneaks up behind you (off camera) and surprise attacks will be good for a jump scare.
The original film kitchen scene:
This scene is suspenseful and legitimately quite scary, even though the raptors are ultimately unsuccessful and the children are not injured in any way. The first thing the raptor does is open the door that they closed behind them to hide. The second thing it does is 'call for back up' when it figures out its prey is present. While slowly stalking the children through the kitchen, the emphasis is placed on the click of the claws on the tile floor. At one point, one jumps up onto the countertops while the other stays at ground level so that they can cover more ground thoroughly. The raptors are very responsive to smell, sound, movement, etc. They're on high alert and 'stalking'.
The 'long grass' scene in
The Lost World:
Here, you barely see the creature. The emphasis, rather, is on how they hunt together as a pack, surrounding and closing in on their unsuspecting prey. You see the heads pop up and catch the light/motion/movement/shouts. And you see the path of the men in a straight line across the field, as many other lines showing the progress of the raptors open up around them. Mostly, it's their tails, though there is a single shot of a raptor leaping on a man.
The 'clever girl' scene in the first film:
This is about the hunter becoming the hunted. Unlike the scene with the pack of little compsognathus overtaking a grown man for...some inexplicable reason...here you have two raptors working together to fool the human hunting them. It is very believable that he's a goner.
And of course, the give away that these are the scary villains and focus of this film "Try to show a little respect." We get the setup and explanation up front.
Granted, in
Jurassic World, there is a bit of working with the raptors rather than against them.
Blue is genuinely likable. The main villains aren't the velociraptors any longer.
I have been watching my cat crawl out of a cardboard box that isn't as tall as her, and that reminds me of the scene in
Return of the King where Shelob emerges from the rock crevice. Your first thought is meant to be...no way that monster fits in there. We could have one of the cats make a similar type of appearance, practically oozing out of a small passageway he shouldn't even fit in. First you just see the head and front paws, and as the body emerges, you realize how big the beast is (would work with any of the wolves, too).
We can have a cat silently watching a scene (from above?) for a long time, and the characters are unaware the cat is even there. But when the camera reveals the cat's location, it's clear the cat was there all along.
A cat can silently appear out of nowhere....taking advantage of 'with cat-like tread'. We can show them lower their heads, stalk forward belly low to the ground (fixed on their prey), and then pounce with a surprising reach and speed.
Playing with their food is one of the things that makes cats particularly cruel. They put a paw on the bug, mouse, etc that they've trapped...and then let the paw up to see if the trapped critter will run. They bat at it a bit. The cat in
Watership Down asks Hazel, "Can you run? I think not...." Very...cat-like. We want Tevildo to be a torturer, so doing something painful and then just watching almost clinically before repeating the action. Just to see what the prey will do. Plenty of opportunity for the cats to 'bat around' elves, slash at them, etc.
In other words, what I'm trying to say is that character design is part of this, certainly, but how you utilize the character is a lot of it, too. We don't just want to show Tevildo (and his cats) snarling and snapping at elves. We want to make them menacing, slinking-in-the-shadows characters whom we see, but worry about when we can't see. They won't be the stars of the show the way the velociraptors are in
Jurassic Park. They're minor side characters, while the 'true' villains are other characters. The cats are more like
dilophosaurus - perhaps a memorable scene here or there, but not an overall arc. But still...their characterization can be nightmare fuel, if we do it right.