This is based on opinion. Please don't list it on a work's trope example list.
Nightmare Fuel / Carnosaur
The novel's Tarbosaurus subverts a lot of tropes in fictional portrays regarding its next of kin, Tyrannosaurus rex. It thoroughly averts the Noisy Nature one might think a predator of its size would have, very rarely vocalizing, walking deceptively quietly, and stalking the humans across the Penward compound.
It also proves to be a The Juggernaut when it comes to opposition. Shotguns, rifle fire, getting hit by a car, and an entire pride of lions barely slow it down. It takes getting its ear ruptured by high strength fire hoses and having a building dropped onto it to finally put it down.
Even with the ridiculous premise and some of the stiffest, most unconvincing dinosaur effects ever not to be produced by Syfy, the first film is still a very moody, very ominous, very bloody piece of work.
The scene where the Deinonychus finds a group of hippies who chained themselves to bulldozers and viciously mauls all of them. What's worse, all of the group could hear their friends being torn apart but are both completely unable to help them or free themselves to get to safety. The thought of being trapped in an isolated area with a monster ripping your party apart one by one while you can't get away is genuinely terrifying.
The death of Sarah Rawlins in Carnosaur 2. Most of the character deaths happen via a Gory Discretion Shot but for Rawlins we see it in fully graphic detail. After she's dragged out of the elevator by a deinonychus, Rawlins is thrown against a wall, where the dinosaur proceeds to slowly bite her arm off, exposing strands of muscle and bone. She's then finished off when it bites into her stomach and eats her innards as she coughs up blood and spasms to death. Of all the ways to go out, this was a really horrifying and Cruel and Unusual Death.