The orca (Orcinus orca), commonly known as the killer whale, and sometimes called the grampus, is the largest member of the oceanic dolphin family.

It is the second-most widely distributed mammal on Earth (after humans) and is found in all the world's oceans. It is also a versatile predator, eating fish, turtles, birds, seals, sharks and even other juvenile and small cetaceans. This puts the orca at the pinnacle of the marine food chain.

The name "killer whale" reflects the animal's reputation as a magnificent and fearsome sea mammal that goes as far back as Pliny the Elder's description of the species. Today it is recognized that the orca is neither a whale (except in the broadest sense, i.e., the sense that all cetaceans are whales) nor a danger to humans; no attack on a human by an orca in the wild has ever been recorded, though there have been isolated reports of captive orcas attacking their handlers at marine theme parks.