The xenomorphs of Alien will hunt down and kill (or capture for impregnation) anything and everything near them. One theory raised by those making the movie was that the aliens were created as weapons of war, so that would also make their actions plausible. The prequel Prometheus justifies the xenomorphs' persistence with The Revealthat they are merely a by-product of the Engineers' bio-weapon. Like everything else spawned from the black goo, the xenomorphs' only purpose is to wipe out all life. Alien: Covenant further establishes that modern-form xenomorphs are specifically a result of David's experiments mixing this chemical with the embryo of a parasitic wasp-like lifeform native to the Engineers' home planet.
The aliens in Alien Abduction (2014) seem to be pretty insistent on getting all of the Morris family, though it isn't clear where it's the same group of aliens chasing them the entire time, or if they keep encountering different groups that are all hunting on Brown Mountain that night.
Anaconda combines this with Artistic License – Biology, stating that the anaconda is some kind of Blood Knight that enjoys killing so much that it will regurgitate its latest meal just so it can hunt and kill again. Needless to say, no real reptile would waste energy like that. Anacondas and other giant snakes were once thought to do that, but it turns out they only regurgitate their food if they're overly threatened while lethargic (btw, the snake in the movie should find a safe place and go into a self-induced coma after eating just one guy, nevermind a whole boat), or because they're, y'know, getting sick off it. Strangely, the movie also at least partially justifies this trope due to the fact that the protagonists in question spend pretty much their entire time in the anaconda's territory hunting it, so its actions could come off as self-defense, aforementioned Blood Knight tendencies aside, as well as the fact there's more than one giant anaconda.
Anacondas: The Hunt for the Blood Orchid: Played with. The jungle expert notes that there's no way a single anaconda, even a giant one, is going to pursue the others after already eating one of them. However, the film justifies the trope by explicitly featuring a large group of hungry snakes who are all in the same area because of a mating season and the humans simply cannot avoid running into them. The travelling male snakes are hyper-aggressive for the same reason.
The Syfy Channel Original Movie, Attack Of The Sabretooth, gives an unusual justification for why the titular beasts keep hunting people even after they'd realistically be full. They're bulimic and keep regurgitating everything they eat so they're always hungry. How and why a bunch of prehistoric big cats all have psychological eating disorders is a whole other can of worms, however.
In the shark horror film Bait 3D, the sharks persistently hunt the surviving humans. It becomes more believable at the end when it's revealed that the sharks were actually trapped in the convenience store along with the people and couldn't just swim away.
The trailer for Beast (2022) has a safari guide lampshade how out of character this is for a lion, implying that it's no ordinary predator. It later turns out the lion attacks humans out of anger after poachers killed its pride.
"I've never seen anything like this: multiple kills, without eating its prey."
The paperboy in Better Off Dead, who pursues Lane on his bicycle throughout the whole movie to get the two dollars he owes him. Highlights include apparently multiplying in one chase until there's half a dozen identical paperboys chasing him, chasing him in the middle of the climactic ski race between Lane and Roy Stalin (still on his bicycle while wearing skis,) and even rushing him and Monique in the last few seconds of the final Flyaway Shot of the movie.
Blood Surf: The crocodile pursues the main characters all the way through a jungle just for a chance to eat them.
The Tiger in Burning Bright. Justified in that the Tiger was starved for nearly a week, and there was no other food supply.
The titular Cocaine Bear which is far more aggressive and persistent than a black bear has any right to be. Justified as it's almost always either high on cocaine or trying to feed its cocaine addiction.
The cannibals of The Colony (2013) never stop, despite the fact that chasing the protagonists is killing them off quickly. Perhaps justifiable since they really have no other source of food.
An inversion in Cool Hand Luke: when Luke escapes prison, he runs so persistently that the bloodhound trailing him runs itself to death.
In Crawl, real alligators would generally try to find somewhere sheltered to hunker down during a hurricane, not go hunting. However, the gators are shown to have built a nest in the basement, so not only are they hungry, they also have eggs to defend.
Justified in Crocodile (but not so much the Sci-FiOriginal sequels third and onward), featuring a crocodile (giant, naturally) pursuing a group of half-dressed teenagers. One of them had one of her eggs in his backpack, fueling her maternal rage. The survivors are allowed to leave when they return it. However, while real life crocodiles actually do have fairly strong protective instincts, they wouldn't chase after someone, and if a nest robber got away from it, it's not going to bother to chase it down.
The sharks in Deep Blue Sea. Tom Jane even points out that sharks don't particularly like the taste of people. Justified because eating the people isn't the goal; getting them to open doors and flood the facility is. Although wiping them out is a beneficial bonus since no one else would know about the super intelligent sharks...
The sea worms in Deep Rising, who continue to relentlessly pursue the heroes despite suffering extreme gunfire trauma from doing so every time. Although the fact the opening of the movie shows an underwater graveyard littered with ships and whale skeletons implies the creature isn't indiscriminate on what it eats and has made a habit of snacking on human ships for quick meals. Since the "worms" are really the tentacles of a scarily intelligent octopoid, it's possible the creature correctly sees the gun-toting humans as a threat to be eliminated more than a meal.
This trope is the premise of The Ghost and the Darkness. This is also a true story; the lions are stuffed and on display in the natural science museum in Chicago. Later studies have suggested that between the two lions, they only ate some 40 people; still a lot, but not the 140 originally claimed.
The baby Zillas in Godzilla (1998). As newly hatched animals, not only should their first priority be to feed themselves, which is easy given the abundance of available fish, but they should be starving and exhausted from the effort of hatching. Worse, they all start competing over an incredibly small number of people to eat (even at some points seeming to start fighting among themselves over who gets to eat the people). Actually justified, as all fish is gone by the time they start chasing humans (who smell like fish).
In Godzilla (2014), Godzilla tracks the MUTOs from one side of the Pacific to the other. Justifiedconsidering Godzilla considers the entire Earth its territory and the MUTOs are an active threat to the biosphere, as well as the fact they're explicitly parasitoids which utilize his species as a host, so he has a personal reason to prevent them from breeding (outside of fighting each other just being what kaiju do naturally).
The Grey features a pack of Savage Wolves as a central plot point. Justified, because the humans were unknowingly moving deeper into the wolves' territory. The last guy finds himself in their den.
It from It Follows, the closest definition of the trope that you can get. Once it targets you, it never gives up. It will always hunt you and will always find you. It cannot be killed or trapped. The only way to stave it off, is to have sex with someone else, but when It targets and kills them, it comes right back after you... That said, it's definitely a supernatural monster so it's justified.
While the shark in Jaws is not much of an example, as it behaved much like an actual predator, the sequels play this very straight. Taken to ludicrous extremes in Jaws: The Revenge, apparently tracking down people over hundreds of miles (while our protagonists are in an airplane) in order to kill them in revenge for their father having killed a couple of other sharks a decade earlier. The novelization claimed this was due to an unexplained Voodoo curse, thus naming the Voodoo Shark trope.
Combined with Humans Are the Real Monsters, Jumanji gives us Van Pelt, the most dangerous thing the game can unleash. Any other predators it unleashes are opportunistic, will target anyone with impunity, and will even go idle or just do their own thing. Van Pelt is hell-bent on hunting and killing whichever specific person rolled the dice and unleashed him, to the point he actually goes out of his way to not kill anyone else or any other players. Even when he has Sarah dead-to-rights in his scope, who is fleeing with the titular board game he intends to use as bait to lure Alan, he instead shoots a rack of tires to block her escape.
Van Pelt: Stop that cringing! I could have killed you at any moment!
Sarah: Then why didn't you?
Van Pelt:You didn't roll the dice. Alan did!
The Jurassic Park franchise plays around with this trope, particularly with Tyrannosaurus rex and Velociraptor:
The T. rex only seems to play it straight when she's chasing the jeep at a suicidal speed for her species, but it's quickly subverted when the jeep accelerates beyond 30 MPH and she soon gives up the chase. Given that she only kills one human and spends most of her time hunting other dinosaurs, it is possible that she's not really hunting humans for food as much as she's establishing new territory for herself and chasing away potential rivals.
The Velociraptors, on the other hand, are portrayed as vicious killers that need to be locked away in a cage. They always try to break out of their enclosures, and specifically targets humans as their preferred choice of prey. It's also implied that, due to their intelligent brains, they hunt for sport, explaining why they still pursue the surviving humans even after killing enough prey to feed them for the day.
A flock of Compsognathus is willing to attack a full-grown man and chase him to the point of exhaustion until he's too weak to fend them off when they tear him to shreds, but they only do this when he's separated from the rest of the group, unarmed, and injured from a fall. The group's paleontologist actually lampshades the little dinosaur's aggressive nature, stating that with no human contact for years, the compys have no reason to fear humans. Depending, the compys might be smarter than they seem, since said human victim previously zapped a compy with his cattle prod basically for the sake of doing so.
The Velociraptors are again vicious brutes determined to hunt every human in their vicinity though this time there is a legitimate reason for it. In order to get off the island, the protagonists need to get to an abandoned facility in the island interior and radio for rescue. The problem is that the facility area is also raptor territory and humans are easy prey for them, especially when disorganized.
They also stumble upon a Tyrannosaurus eating a dead dino with plenty of meat left, but when it sees the humans, it naturally starts pursuing them instead. Which incidentally leads it to the Spinosaurus, whom it engages and is killed by. It might have perceived them as a threat to its meal and is chasing them off ... in which case it ought to have stopped chasing them as soon as they were out of sight and gone back to its food.
The Velociraptors of this film, however, chase the heroes because one of them secretly steals their eggs. When the eggs are returned safely, they leave without attacking.
The film justifies the Indominus rex's persistence by establishing that she's a hyper-aggressive super-predator that is killing for sport rather than for food. However, in one scene, the I. rex gives up on chasing a pair of human children because they jumped over a waterfall and swimming is seemingly the one thing she is unable to do.
An overly eager Pteranodon tries to fish out Zara from the lagoon with the intent of eating her despite the fact that she, as a full-grown woman, is too heavy to be lifted with its beak. The constant splashing eventually attracts a Mosasaurus who proceeds to eat both Zara and the Pteranodon in one swift bite.
The Velociraptors here have been tamed into a manageable squad by Owen Grady, but are still dangerous and will attack any stranger or human they simply don't like. But they're not single-mindedly focused on hunting down all humans until the Indominus rex usurps Owen's authority and commands them to kill their human allies. From that point, the raptors begin pursuing every human they can find, including a fast-moving jeep heading all the way down to Main Street.
In Jurassic World: Fallen Kingdom, the predators in Isla Nublar seem to place their hunger above their basic survival instincts:
Even as Mount Sibo showers the island with flaming rocks, a Carnotaurus takes its sweet time hunting a Sinoceratops and Owen instead of joining the stampede.
Rexy herself ignores the volcanic eruption at first to attack the abelisaurid, thus keeping up the trend of her being an Accidental Hero.
The Baryonyx chases Claire and Franklin into a shelter that is being filled up with lava, not giving up on its prey even after being splashed in the face with the stuff multiple times. This is specially jarring when the official website mentions the Baryonyx as a species is only mildly aggressive and used to be part of an attraction where visitors would go kayaking at its territory.
The only justified example is the Indoraptor, which is a successor to the I. rex from the previous movie and is just as ruthless and sadistic as she was.
The film later zigzags the trope when the carnivores and herbivores completely ignore each other upon being released into the garage of Lockwood's estate, as one would expect from a group of animals that are more concerned with avoiding being poisoned by a damaged ventilation system.
Jurassic World Dominion has an engineered case in the Atrociraptor, which is a successful attempt at a trained killer dinosaur that the above mentioned Indoraptor was supposed to be. And 'persistent' is the key word, as once it is assigned a target, Atrociraptor will pursue it even as it rides motorcycles and cars, and through rooftops and cramped rooms.
While all of the predators of Skull Island in King Kong (2005) seemed to want to try out the new taste sensation of white people more than the next one, none were worse than the V. Rex who actually runs after Ann Darrow with the corpse of a current kill in his mouth. Some of the V. Rexes on the island actually sacrifice themselves in their attempts to kill her. And when given the chance to bite Kong versus swallowing Ann, they always went for Ann. The Venatosaurusraptor-pack comes a close second, trying to chomp humans in the middle of a Brontosaurus stampede, then persisting in chasing down hapless cameramen, rather than gorging on several thousand tons of fresh bronto meat that was lying there waiting for them.
Justified in Komodo. The komodos relentlessly pursue the protagonists, but there are several of them and they are stated to be starving. The behavior may also have been inspired by the outdated belief that real komodo dragons do this, namely bite large prey and then follow it relentlessly until it keels over from infection and venom. This has since been indicated to not be the dragon's actual hunting strategy. Normally if a animal escapes a komodo dragon then it's a failed hunt for that dragon. Another komodo may take advantage of the injured animal later, but the original isn't going to bother tracking an escaped animal very far. Typically komodos kill their prey relatively quickly via massive blood loss and perhaps help from the venom. Even the infection strategy may be more coincidence than intention (injured water buffaloes retreat to dirty water that causes their wounds to become infected, but the infection is not intentional on the part of the dragon).
Kong: Skull Island: The Skullcrawlers on Skull Island are literally called the "persistent enemy" in the Iwis' language, never stopping once they've targeted prey due to their Horror Hunger. An earlier script also had Marlow nickname the biggest Skullcrawler "MacArthur", because it never gave up.
Played with in the 2009 Land of the Lost movie. The resident T. rex, Grumpy, actually is all set to give up on chasing Marshall, Will, and Holly after they prove to be more trouble than they're worth. That's until Dr. Marshall insults the T. rex's intelligence, causing it to hold a grudge against him for the rest of the film. Marshall keeps insulting it several more times, just as it seems the T. rex is ready to give up, fueling the creature's rage.
TV B-MovieThe Last Dinosaur has the titular titan, a T. rex with Implacable Man tendencies, treat a group of explorers like this ... at first. Then we see it kill and eat everything unlucky enough to cross its path. Implicitly, it's eaten most every other animal in the Lost World.
In The Meg, the second Megalodon pursues the protagonists' motorized dinghy for over ten miles before a couple of attack helicopters finally drive it off.
In the A24 horror film The Monster (2016), the titular beast kills just about everything it comes across, even when it has no realistic reason for doing so. It starts the movie by snacking on a wolf and proceeds to kill and eat a grown man before setting its sights on the mother and daughter protagonists. It then kills two paramedics and continues chasing the protagonists when they try to drive away from it. After a while, it seems like everything it does may simply be For the Evulz.
The killer whale in Orca: The Killer Whale. Justified in that it was out for revenge, something dolphins regularly do in Real Life, though in the film it was portrayed as a male avenging his mate and child (making it more like an aquatic Death Wish than a Jaws imitator) when in reality it would be a whole pod avenging one of their friends.
Onibaba in Pacific Rim was very determined to kill a young Mako. It's implied, though, that being a memory, this scene wasn't meant to be a literal retelling of events but rather the skewed representation of a scared little girl in the middle of a Kaiju attack. Though it would be justified, since the kaiju are not natural predators, but bioweapons created solely to wipe out humanity. That means every single human, even a little girl, has to die.
The last stretch of Prophecy has the main cast dealing with a literal (mutated) Mama Bear that wants to get them no matter what.
A Quiet Place: "If they hear you, they hunt you". Often these hidden creatures, who are blind (and apparently don't have a sufficient sense of smell) but hunt by sound and are very fast and near indestructible, home in and strike very quickly if you make a noise — but if you evade them, they'll still prowl around, listening very closely for further sound or movement, and not go away....
R.O.T.O.R. revolves around the titular police Killer Robot accidentally activating and going on a rampage by following its primary program to be a Judge, Jury, and Executioner. The full extent of said rampage is the implacable chase of a poor woman who was a passenger to his first kill (a Jerkass who was speeding) on the apparent charge of being an accomplice and resisting arrest, which covers several hundred miles of Texas backroads and takes at least one whole day.
In The Shallows, the shark repeatedly attacks Nancy and kills several other humans who get into the water even though there is a whale carcass nearby. It is implied due to the scars on its face and the spear stuck in its side that it has had a bad history with humans and attacks them out of anger.
Shark Attack: The sharks are intentionally (and as the hero — who's a marine biologist — notes, rather uncharacteristically) going after humans. This is initially thought to be because overfishing is driving them to look for prey at the shorelines, but it's later revealed to be because a guy with a Morally Ambiguous Doctorate was spiking them with hormones.
Star Trek (2009): Used as padding in. Kirk is being chased by some shambling furry thing. Then a giant red animal with multiple limbs and a Flower Mouth bursts out of the ice, bites the furry thing, tosses it aside... and starts chasing Kirk. Even though the shambling furry thing was bigger (but still bite-sized to it) and it had already killed it. It also frequently stops to roar at Kirk. Eventually, Spock Prime is able to run it off with a flare.
J. J. Abrams is very fond of including these in his Sci-Fi movies. Like in the previous example, he invented Rathtars for The Force Awakens, which are giant red tentacled blobs covered in yellow eyes with gaping maws full of teeth. They attack anything they can get their tentacles on with blinding speed. The general rule of an Abrams Sci-Fi movie is that he won't even look for an excuse to include a big red monster with tentacles and pincers and far too many teeth with a desire to rapidly chase the main character(s) just for kicks.
In Kaw, Creepy Crows get infected with Mad Cow (?!) disease after eating clearly diseased rotting cow flesh. As soon as they go crazy, they decide to exclusively go for the human protagonists (not even any other areas, just those few people). This includes waiting on a bus while the humans cry and then throwing rocks at the bus in a desperate attempt to get inside. Later, they slam themselves against a diner in order to get in and eat the people inside, before they inexplicably die. You'd think there weren't any animals in the forest. Subverted in that the super persistent predators starve to death, just as they would in real life.
Shockingly averted in the (surprisingly good) reimagining of The Land That Time Forgot (which starred and was directed by C. Thomas Howell) in which the Rex only chases the humans when they enter its territory to steal food, and all it does is just try to run them off.
The Graboids in Tremors. Earl compares their patience to that of Job. They track prey endlessly, and if the prey is somewhere they can't reach, they wait it out for days if need be. The only time they'll leave is when the prey dies of dehydration/starvation or if they're distracted by a sufficiently loud noise/vibration nearby that screams "easier meal" for them.
Ultraman Saga: Early in the film, there's a Gubila (a kaiju narwhal, imagine something like a Land Shark) which relentlessly pursues Taiga and a little boy he befriended throughout the deserted city, from the streets to above a bridge, for maybe three minutes without stopping, even destroying said bridge just to catch two tiny humans.
", because it never gave up.