The Meg

The Meg, also known as the Megalodon, is the titular main antagonist of underwater thriller novels of the same name, and the 2018 film based off of it. Megs are fearsome, sadistic, and extremely massive prehistoric shark who terrorizes anything that stands in her way.

Book
The Meg was accidentally released from the Mariana Trench by Jonas Taylor, who was examining the wreck of a submarine. The wreck was also caused by the Meg. This Meg wreaked terror until Jonas Taylor dove into the shark's mouth and used a Meg tooth he had found a few years before to rip out the heart of the creature. But before that happened, the Meg gave birth to a pup named Angel.

Movie
The Meg at first attacked a submarine. However, it was so large and unseen, that nobody knew yet what the cause was for the accident of the submarine. The submarine's crew of divers went to find out what caused the accident. They at first blamed a giant squid for doing so, but then the Meg ate the squid.

As the crew rushed back into the submarine, and the Meg came back, Toshi sacrificed himself to that shark.

The crew eventually realizes that the Meg is actually the largest Megalodon to ever live on Earth. The crew dive again and manage to find the megalodon and poison it with a large dose of etorphine, killing it. However, it is revealed that the shark which they've killed is another shark, possibly a male Megalodon (since male Megalodons were smaller than female Megalodons). Suddenly, a much larger female Megalodon jumps out of the water, unknowingly swallowing the Wall alive; who had been swimming in the water after being pranked, and grabs the dead Megalodon and pulls it back into the water. The Meg also kills Heller, who had distracted her so she wouldn't kill Jaxx, and wounded Zhang, who eventually dies from his injuries.

That night, Morris orders a helicopter crew to drop depth charges at the Meg but realizes that she tricked them by using a whale carcass. The Megalodon chases after his boat, causing him to fall overboard. He swims back to the carcass and climbs onto it, only to get devoured by the Megalodon as she bites into the whale carcass, leaving only his hands.

Later, the crew learns that the Meg is heading towards a crowded beach and could kill dozens of swimmers near Sanya Bay.

The Meg manages to get near the beach and its swimmers, The Meg starts to attack the swimmers. And manages to devour just a few. However, before it could eat another crowd of swimmers, the crew on the submarine used dolphin sounds to attract the shark and keep it away from the swimmers. The Meg then attacks the boat, but does little damage to it. However, two news reporter helicopters who were watching the shark carresly collided into each other. Causing one of them to crash into the ship. Forcing everyone to jump into the water.

Jonas Taylor, the leader of the diving crew and the film's main protagonist, decides to make the Megalodon bleed to death. He tries to hunt the Meg as Suyin (the Chinese woman of the crew and second mate) backs him up with her own submarine. Taylor's submarine, however, gets attacked and heavily damaged by the Meg, and thereafter, his submarine cannot move anymore. Taylor swims beneath the fearsome shark and manages to cut its stomach open using his damaged sub. After that, he swims back to the shark's front and uses his poisoned spear to stab the Meg through its eye, killing it instantly. The blood causes other sharks nearby to smell the dead Megalodon. Therefore, the other sharks came and ate the corpse of the Meg.