What eats Orca?

Answer 1

Adult Orcas can be eaten buy Adult Great White Sharks and their calf's can get eaten by packs of tiger sharks. Sharks eat Killer Whales.
Orcas are considered apex predators however their was proof of a large male great white shark attacking and then eating an orca male. Their have been other attacks to of a shark eating an orca so the great white shark is a predator of the orca. What great whites do to kill the orca is to either attack them by surprise by going under on the side or over the killer whale to then bite them. But their was a attack on video with a great white shark going front on the the killer whale and biting on its neck. Great whites can also attack baby orcas.
It almost never happen but sometimes a sperm whale can eat an orca (or killer whale)
Humans are the only predators of killer whales. The killer whale is an apex predator and therefore has no natural predators.
Nothing unless the whale's already dead. Then some scavenger fish or crabs might feast off of the carcass.

Various types of shark are known to follow pods, hoping for a slow calf, elder or ill Orca to fall behind, losing the safety that the group provides.
Killer Whales are one of the top predators of marine life. Sometimes, though, orcas that may possibly sick and weak may get caught and eaten by other predators like a polar bear or possibly sharks. Orcas that beach themselves and die get eaten by all sorts of scavengers, from gulls, eagles and ravens to bears, wolves, and foxes.
Sometimes Killer Whales (or Orca's) are eaten by any kind of shark but is very rare. It is also rare for a Killer Whale to eat a shark but does happen... Killer Whales don't have predators!

Answer 2

Various types of sharks will trail a pod of Orca, hoping for a slow calf, elder, or sick Orca to fall behind and lose the safety provided by the group.