Predators

The killer whale is the narwhal's most common predator. There are documented accounts of killer whales herding narwhal toward the shore, where they are more vulnerable, although it is not unknown for killer whales to attack in the deep sea. The movement and distribution of herds of narwhal can be very much affected by the near presence of killer whales, as narwhals will try and avoid them whenever possible.

Polar bears have been known to attack narwhal when they become trapped in the ice, and observers have even reported sightings of narwhal scars resembling marks made by a polar bear's claws.