(genus Lamna), any member of a group of sharks in the family Isuridae. The name is also used as a collective name for the family, which includes, in addition, the white shark and the mako shark groups.

The genus Lamna includes the Atlantic mackerel shark, or porbeagle (L. nasus); and the Pacific mackerel shark, or salmon shark (L. ditropis).

Mackerel sharks are swift, active fishes with crescent-shaped tails and slender teeth, most of which are flanked by small, sharp cusps. These sharks are gray or blue-gray above and paler below and grow to a length of about 3 m (10 feet). They inhabit temperate waters and prey on fishes such as herring, mackerel, and salmon, sometimes taking fishermen's catches and damaging nets in the process. They are fished commercially for food.