killer whales or orca.. top of the food chain... no natural predators...
they have been seen hunting everything from baleen whales to sardines.. and there has been a documented orca which hunts great whites for the liver which is high in fat..
however, they may toy with their prey, which is a natural behaviour akin to cats toying with theirs.. but they have shown their merciful side.. in a documented sighting in Patagonia where they beach themselves to hunt seals, there was once where they had enough to eat already and they had stunned too many seals, an orca was seen helping one back to shore...
they are complex beyond words and are lovely creatures
and there has never been a documented case of a human killed by them