The king mackerel (Scomberomorus cavalla) is a migratory species of mackerel of the western Atlantic Ocean and Gulf of Mexico. It is an important species to both the commercial and recreational fishing industries.

The king mackerel is a medium-sized fish, typically encountered from five to 30 pounds, but is known to exceed 90 pounds. The entire body is covered with very small, hardly visible, loosely attached scales. The first (spiny) dorsal fin is entirely colorless and is normally folded back into a body groove, as are the pelvic fins. The lateral line starts high on the shoulder, dips abruptly at mid-body and then continues as a wavy horizontal line to the tail. Coloration is olive on the back, fading to silver with a rosy iridescence on the sides, fading to white on the belly. Fish under 10 pounds (5 kg) show yellowish-brown spots on the flanks, somewhat smaller than the spots of the Atlantic Spanish mackerel, Scomberomorus maculatus. Its cutting-edged teeth are large, uniform, closely spaced and flattened from side to side. These teeth look very similar to those of the bluefish, Pomatomus saltatrix.