Cottoidei is a suborder of ray-finned fishes which, according to the 5th edition of Fishes of the World, is placed within the order Scorpaeniformes, alongside the scorpionfishes, flatheads, eelpouts, sticklebacks and related fishes.

The Scorpaeniformes are a diverse order of ray-finned fish, including the lionfishes and sculpins, but have also been called the Scleroparei. It is one of the five largest orders of bony fishes by number of species, with over 1,320.