The problem: Trope is currently just "work has a megalodon in it" and should be made more narratively specific in the same way as Terrifying Tyrannosaur (work has a T. rex) and Doofy Dodo (work has a dodo) were.
Wick check (as of 02/07/23; see also here):

• megalodon mention: 5/50; 10%
• large shark: 3/50; 6%
• work has a megalodon: 23/50; 46%
• menacing megalodon: 19/50; 38%
• unclear: 1/50; 2%

Proposed solution: Rename to "Menacing Megalodon" (still a sub-trope of Threatening Shark) and update the scope to "Megalodons or other gigantic (bigger than a great white) sharks specifically portrayed as a bad guy or otherwise serious threat to people" (this would allow examples of heroes using megalodons against their enemies to stay) and subversions ("Megalodon who's friendly"); remove the examples that are just "Megalodons exist or are referenced". 44 out of 64 on-page examples already fit this description or can be updated to reflect it. The definition would also need to be updated to reflect this.
A UsefulNotes.Megalodon page could also be made for general discussion on the species, incorporating much of the current trope definition and assimilating the contents of the existing "Real Life" folder.

1. Main.Names To Run Away From Really Fast: Quite a few names of dinosaurs (and other prehistoric animals) count as this, including Deinonychus ("terrible claw"), Deinosuchus ("terrible crocodile"), Megalodon ("great tooth") and, of course, Tyrannosaurus rex ("tyrant-lizard king"). megalodon mention
2. Main.Stock Animal Diet: Humans, or anything else in the ocean (including fish, which is true). Seals and sea lions in more accurate works, with different species having different preferences. The prehistoric Megalodon is always shown eating whales, which is accurate to fossil findings of whale bones with C. megalodon bite marks. megalodon mention
3. NewerThanTheyThink.Animals And Plants: Megalodon is often shown coexisting with and going extinct along with the dinosaurs, even in works which carefully avoid making the same mistake with other popular Cenozoic creatures like mammoths and sabre-tooth cats. In reality, the giant shark first evolved around 15.9 million years ago, almost 40 million years after the dinosaurs died, and died out about 2.6 million years ago — after the evolution of bipedal apes (but before that of true humans). megalodon mention
4. UsefulNotes.Stock Dinosaurs Non Dinosaurs:
   • Basilosaurus has been a recent hit in documentary media since the 1990s and especially the 2000s; see Walking with Beasts for an example. But it hasn't received the same amount of attention in broader popular culture as other giant sea critters of the past (Elasmosaurus, Megalodon, Mosasaurus). megalodon mention
   • Other similar contemporaneous sperm-whale relatives with smaller size and smaller (but still huge) teeth have been found in different places of the world about the same time of the discover of Livyatan, or a bit earlier (the first emerged in the nineties): their scientific names recall the one of the modern giant sperm-whale, Physeter, with a prefix ahead. They were: Acrophyseter from Peru, Brygmophyseter from Japan (portrayed in Jurassic Fight Club as the rival of Megalodon), and Zygophyseter from Italy. Overall, Lyviatan and all these cetaceans are nicknamed "macroraptorial sperm-whales", or more simply, the Macroraptorials. They could not form a natural group, though, but all them were related with the true sperm whale of the modern oceans. megalodon mention
   • Obviously, this animal is often shown in documentary media: for example, its open jaws are often depicted with some people inside to show how immense they are. Recently, this animal has fascinated the world of fiction, to the point that Megalodon has become a trope on its own. But wait: Megalodon (literally "big tooth") is not the name of its genus; it's that of its species. The full scientific name used to be Carcharodon megalodon; today it's Carcharocles megalodon. It was believed to have been an extremely close relative of the great white shark (Carcharodon carcharias); today it's placed in a different family convergently similar to the great white's, but still in the same order of true sharks: the Lamniformes, which also include the long-tailed thresher sharks, the filter-feeding basking shark, the deep-sea megamouth shark, and the toothy-grinned sandtiger sharks, among the others. megalodon mention
5. WMG.Pokemon Future Species: A Megalodon. megalodon mention

1. AudioPlay.Tigers Eye: From the description we get of the Widow of the Waves, it appears to be a monstrously large shark. large shark
2. Characters.Pathfinder Beasts: The isonade is a massive Gargantuan-sized shark-like creature, like the real Carcharocles megalodon itself. large shark
3. Film.Pinocchio 2002: The Terrible Dogfish in this adaptation is depicted like a huge Threatening Shark. large shark

1. ArtisticLicensePaleontology.Literature: While they aren't about dinosaurs, Steve Alten's Meg novels will make paleontology enthusiasts cringe. The opening scene of the first book has a T. rex chasing some hadrosaurs into the water, where it is eaten by a Megalodon explicitly stated to be twice its size. *sigh* Carcharodon megalodon did not live during the Cretaceous (the giant shark appeared 47 million years after the dinosaurs died out). work has a megalodon
2. ArtisticLicensePaleontology.Live Action TV: Timecop: Ian Pascoe claims to have witnessed a Megalodon shark rip the throat out of a Tyrannosaurus rex. These animals lived over 47 million years apart, assuming he didn't somehow (?) bring them together. work has a megalodon
3. ArtisticLicensePaleontology.Video Games: Scribblenauts: The words Dunkleosteus, Bull Shark, Cow Shark, and Sixgill Shark summon a Carcharocles megalodon. work has a megalodon
4. Awesome.Walking With: From the special Sea Monsters Nigel Marven tagging the giant shark Megalodon. work has a megalodon
5. Characters.ARK Survival Evolved: Similar to this game's Tyrannosaurus, this creature is consistently referred to as "Megalodon"; with the word being a species epithet, it had to be changed to make the game's species different from the one Real Life. As such, the real species name here is Carcharodon ultramegalodon. work has a megalodon
6. Characters.Kamen Rider Revice Deadmans:
   • A Megalodon-themed Deadman created from the Megalodon Vistamp by disgraced pro golfer Araki after he saw the demons' power in action and was encouraged to go seek out the Deadmans cult by Vice. work has a megalodon
   • Its main Animal Motif. work has a megalodon
7. Characters.Pathfinder Animals: Megalodon is the alternate name of the Gargantuan-sized dire shark. work has a megalodon
8. Characters.Ravenloft Darklords Beyond The Core: There's a chance that any shark he summons will be one of these, for added fun. work has a megalodon
9. Characters.Splatoon Idol Groups: Shiver claims that her pet shark's species is a Megalodon. Which explains the oversized nature of Master Mega, though it does raise questions as to how a Megalodon managed to stay under the radar between two extinction events. work has a megalodon
10. CreatorBacklash.Live Action TV: The Discovery Channel has walked-back on their Shark Week special Megalodon: The Monster Shark Lives, a Mockumentary that claimed that the Megalodon was still alive. For the 30th anniversary of Shark Week, they released Megalodon: Fact vs. Fiction where scientists pointed out the original special's inaccuracies, as well as taking potshots at the bad acting and visual effects.
11. Fanfic.The Swarm Of War: A Zerg Sea Monster type. It’s even called the Carcharlisk. work has a megalodon
12. Funny.Justice League Throne Of Atlantis: Black Manta casually mentioning during his Motive Rant that Orm "Irks the shit out of [him]"... and then Aquaman calls in a Megalodon from out of nowhere. work has a megalodon
13. Funny.Roblox: One of the monsters in The Scary School is a Threatening Megalodon playing "Baby Shark" in low pitch. Now that's some Lightmare Fuel. work has a megalodon
14. Literature.He:
    • The story tells of how oceanographer Dr. Woodruth Poplar ends up encountering in an atoll in American Samoa a creature thought to have been extinct for millions of years, a Megalodon. work has a megalodon
    • He is a Megalodon, a gigantic prehistoric shark. work has a megalodon
15. Main.Hybrid Monster: Deadpool: The Megakrakolodonus, created from Deadpool's collection of prehistoric teeth, is a hybrid of a Tyrannosaurus rex, a Kraken, and a Megalodon. work has a megalodon
16. Series.Jurassic Fight Club: Featured in the fifth episode where it fights against the biting sperm whale Brygmophyseter. work has a megalodon
17. ThreateningShark.Video Games (2): Scribblenauts: You can summon sharks. A single Scribblenauts shark is enough to defeat Cthulhu. You can also summon Megalodon. work has a megalodon
18. VideoGame.Scribblenauts: * The words Dunkleosteus, Bull Shark, Cow Shark, and Sixgill Shark summon a Carcharocles megalodon. work has a megalodon
19. Webcomic.Adventure Dennis: The boss of the underwater level. work has a megalodon
20. Webcomic.Tet Zoo Time: Funny Background Event: There are loads in the background of the theme song, including, but not limited to, a Megatooth shark, a pygmy right whale, over-enthusiastic swallowing, a rhinogradentian, and a babirusa, all of which have been featured on Tet Zoo. work has a megalodon
21. WebOriginal.Mortasheen: Threatening Shark: There are a quite a few shark-based monsters. The Gashark is a rotting shark corpse with legs controlled by a Puppeteer Parasite, while the Makkoron is a straight-up Shark Man. The Shrezar is a vampire shark, and the Monstrougeist is part Anomalocaris and part Megalodon. work has a megalodon
22. Website.Badass Of The Week: Megalodon. work has a megalodon
23. WesternAnimation.Dino Squad: The monster in the first episode. It looks more like a mosasaur than a megalodon though. work has a megalodon

1. Analysis.Threatening Shark: The Megalodon, a forty foot — that's the minimum estimate — long prehistoric super shark. Also believed to have had one of the most powerful bite forces in the history of the animal kingdom. As well as a number of other large (and often freakish-looking) prehistoric sharks. Emphasizes the threatening part of the megalodon.
2. Headscratchers.Moana: Judging by the markings and shape of the teeth, when Maui takes the form of a shark he's mimicking a tiger shark. Now his shapeshifting in general seems limited to creatures he has added a tooth or claw or bone from them to his necklace. There is no tiger shark tooth on his necklace. There is a shark tooth on his necklace, but it's the wrong shape to be a tiger shark tooth. In fact, by the size alone, that tooth could only have come from the ancient megalodon shark. Yes, that Megalodon. Even if he does have a tiger shark tooth, say, on the part of his necklace hidden by his hair, why would he choose that form over the much more badass megalodon!? Seems to imply that the megalodon is threatening.
3. Characters.Apotheosis Aedificatoris In Absentia: Threatening Shark: Thekasios' sacred animal is the shark, though it is only threatening to his enemies and is actually used as a mount by his prophets, priests, and holy warriors. Also present in the form of his Sea Monster, overlapping with Megalodon. Megalodon is portrayed as threatening.
4. Characters.Sea Of Thieves:
   • Hunter of Monsters: Successfully brought down a Megalodon at some point. It's head now adorns the interior entrance of the Glorious Sea Dog Tavern. Megalodon is implied to be a threat
   • Founder of the Hunter's Call and huntsman extraordinaire. Originally appeared during the game's first major update, the Hungering Deep, after inadvertently waking the dreaded Megalodon the Hungering One and rallying pirates to band together and hunt the beast down. Implied threat in megalodon
5. Main.Battle Trophy: The Meg: After the mercenaries hired by Jack Morris kill the megalodon, Morris tells a merc to climb onto the floating carcass and collect some of its teeth as a trophy, adding "and grab one for yourself as well." Problem is he can't find any teeth...because they've actually killed a whale, so the megalodon is still out there. Implied threat of megalodon.
6. Main.Eldritch Ocean Abyss:
   • In The Meg, scientists accidentally release a megalodon shark[[note]]Extinct, and thought to be a shallow-water predator[[/note]] from the Marianas Trench. According to the original novel, megalodons are explained to have evolved into an abyssal species but are no less horrifying or threatening for it. One of the characters is also attacked by a Giant Squid, but is inadvertently saved when a megalodon eats the squid. Megalodon is a threat
   • Megalodon: The film is kicked off when a new experimental deep sea oil-drilling rig penetrates through the ocean floor off the coast of Greenland, revealing a Lost World hidden for millions of years inhabited by prehistoric sea life. Among these is sixty-feet of prehistoric terror, a full-grown megalodon that quickly turns the drilling expedition into a fight for survival. Megalodon is a threat
7. YMMV.The Meg: They Wasted a Perfectly Good Plot: Sadly, the film doesn't adapt one of the most famous scenes from the original novel, which is a confrontation between a Megalodon and a Tyrannosaurus rex. Who wouldn't want to see that on the big screen? Megalodon implied to be theratening
8. Main.Never Found The Body: Wonder Woman (2006): Alkyone went into the megalodon protected sea off a cliff on Themyscira and was presumed dead. A few issues later a megalodon that had been cut open from the inside washed up on Themyscira's shore, informing the reader that the villain was making a comeback. Megalodon implied to be a threat
9. Monster.Literature H To M: Megalodon in Paradise, by Hunter Shea: Dr. Mueller is a former Nazi war criminal and the creator of the Megalodon. Forming a way to keep his creation under control, so that it needs to ingest a certain chemical, Mueller provides it by injecting prisoners with it, causing unspeakable agony before they are fed to the shark, a process he continues for years until running out of former Nazis. With a storm approaching and dying of radiation poisoning, Mueller opts to inject himself to bait his creation into breaking out to devour him, knowing it will annihilate their facility and be unleashed upon the unsuspecting world. Megalodon implied to be a threat
10. NightmareFuel.Mermaids The Body Found: The Megalodon attack, where one hunts and kills a whale while its companion decides to make a meal out of the nearby mermaid pod. Megalodon shown to be a threat
11. NinjaPirateZombieRobot.Film: Most of the Syfy Channel Original movies are this. Take Mega Shark vs. Giant Octopus for example, it's a movie about a Megalodon big enough to snap a battle ship in half in one bite that can jump high enough to eat a jet liner about to fight a Giant Octopus big enough to crush an oil rig and levels Tokyo, the two of which have been frozen for eons. Megalodon is a threat
12. Quotes.Eldritch Ocean Abyss: And there was something else - something down there in the black abyssal trenches of the ocean. Something that wanted to rise. What was it? An army of giant squid? Cthulhu? Some last surviving Carcharodon megalodon? Quentin never found out. He hoped he never would. - The Magician's Land Quote implies that the megalodon is threatening—naming it along with Cthulhu, for one.
13. Series.Prehistoric Predators: Threatening Shark: Megalodon is the focus of its own episode, a giant 50-foot shark that was the undisputed apex predator of our oceans for some 20 million years. Though it’s not invulnerable, as smaller but more intelligent and social cetaceans like Squalodon can still Zerg Rush to combat it. Megalodon portrayed as threat
14. Series.Sea Monsters: The third most dangerous Sea Monster is the famous prehistoric shark. Nigel and his team decide it's safer to try swimming with one of the juveniles (already the size of a great white) in the shallows first before moving on to the humongous adults patrolling the oceans—and even then Nigel insists on using a reinforced cage. Megalodon shown as threat
15. Series.Timecop: Artistic License – Paleontology: Ian Pascoe claims to have witnessed a Megalodon shark rip the throat out of a Tyrannosaurus rex. These animals lived over 47 million years apart, assuming he didn't somehow (?) bring them together. Megalodon is portrayed by a character to be a threat
16. TabletopGame.Hollow Earth Expedition: One of the most dangerous predators in the seas of the Hollow Earth is the megalodon, a shark that's more than 100 feet long and weighs more than 50 tons. They feed on whales and plesiosaurs, but avoid attacking the kraken. Megalodon is a threat
17. TheWorfEffect.Literature: There are many examples in Steve Alten's Meg series where a Megalodon defeats equally large and dangerous predators, but only the opening scene of the first novel qualifies (wherein Meg eats a Tyrannosaurus rex) because the marine reptiles are too obscure to the general public to be this trope. Megalodon is threatening
18. ThreateningShark.Video Games (1): Back during the Beta testing period, there used to exist the Megalodon in Lake Rathetear. A shark who's jaw was larger than a hill giant (who themselves stand 20 feet tall). Unfortunately, its sheer size presented many pathing issues while swimming between the various islands scattered around the lake, and had to be removed before the game went live. Megalodon as a threat
19. VideoGame.Age Of Mythology: The Atlanteans have the Nereid, a trident-wielding sea maiden riding a huge shark that can defeat any other water myth unit in single combat. Megalodon is a threat

1. Awesome.Real Life: Megalodon has a reputation for being an extremely badass marine predator, and yet scientists believe it wasn't able to compete with orcas and thus driven to extinction. Some even think the mega-sharks died out because orcas hunted down their young (and perhaps the adults as well). But either way, orcas caused the extinction of a prehistoric whale-eating sea monster. Unclear — mentions the "menacing" part, then says they died out.