- a large tropical and subtropical marine fish, Istiophorus platypterus, of the family Istiophoridae, distinguished by a long, high dorsal fin, long pelvic fins, and a double keel on each side of the tail.
- any of several related fishes having a high dorsal fin.
- any of several large scombroid game fishes of the genus Istiophorus, such as I. albicans (Atlantic sailfish), of warm and tropical seas: family Istiophoridae. They have an elongated upper jaw and a long sail-like dorsal fin
- another name for basking shark
