旗鱼又称为马林鱼，是多种海中大型掠食性鱼类的总称。

大型的种类可超过4公尺长。吻部细长。分布于所有主要大洋。以其他鱼类为食。旗鱼是受欢迎的食物和游钓鱼种。

共有12种：

The term billfish refers to a group of predatory fish characterised by prominent bills, or rostra, and by their large size; some are longer than 4 m (13 ft). Billfish include sailfish and marlin, which make up the family Istiophoridae, and swordfish, sole member of the family Xiphiidae. They are apex predators which feed on a wide variety of smaller fish, crustaceans, and cephalopods.