Wikipedia says:

The megalodon (pronounced /mɛɡlɑːdɒn/ or meg-la-don; meaning ‘big teeth’ or in Greek as μέγας ‘οδόντος) is a giant prehistoric shark that probably lived between about 16 to 1.5 million years ago,[1] and was the apex predator in its time. It is recognized as the biggest known carnivorous fish to have existed. It is often termed the “mega-tooth shark.” The classification of this shark is currently under dispute and a new genus has been proposed for this species. Fossil evidence has revealed that C. megalodon fed upon large animals, including the early whales.

Some cryptozoologists argue that this shark might still be alive today, probably living in deep waters, and often cite the examples of coelacanth and megamouth shark to support their claims.[1] However, such beliefs are considered to be false and lack sufficient credibility. Still, C. megalodon has left a lasting impact on the minds of the people around the world, as a highly fascinating monster, which is evident from the popular culture.