The extinct shark genus that includes Otodus megalodon is Otodus.
Megalodon is commonly written as Otodus megalodon, with Otodus as the genus and megalodon as the species name. It was a giant member of the extinct shark family Otodontidae and lived from roughly 23 to 3.6 million years ago, spanning the Miocene and Pliocene epochs. Its fossil record consists chiefly of teeth and some fragmentary vertebral remains because shark skeletons are made primarily of cartilage.
The classification has changed over time. Older literature often placed the animal in Carcharodon, the genus that contains the great white shark, or in Carcharocles. Similarities between their teeth encouraged that connection, but later studies emphasized differences in tooth structure and evolutionary relationships. Many modern treatments use Otodus, sometimes with the name Otodus (Megaselachus) megalodon.
The genus question is therefore worth asking carefully: “megalodon” is the familiar common name, while Otodus is the genus in the accepted answer used here. Estimates of its maximum size and exact body shape remain debated because the fossil evidence is incomplete. Its extinction date is also discussed, though the species is not considered to survive into the modern ocean.