Megalocottus is a small genus of marine ray-finned fishes belonging to the family Cottidae, the typical sculpins.

Megalocottus was first proposed as a monospecific genus in 1861 by the American biologist Theodore Gill with Cottus paltycephalus which had been described in 1814 by Peter Simon Pallas from Kamchatka and the Sea of Okhotsk as its only species.

[1][2] The 5th edition of Fishes of the World classifies this genus in the subfamily Cottinae of the family Cottidae[3] but other authorities classify it in the subfamily Myoxocephalinae of the family Psychrolutidae,[1] although others place the subfamily Myoxocephalinae within the Cottidae.

[4] Megalocottus prefixes megalo meaning "great" or large" with Cottus, presumed to be a reference to the large size of the type species.

[5] Megalocottus currently contains two recognized:[6] Fishbase retains these two species as valid, other authorities treat the Southern flathead sculpin as a subspecies of the belligerent sculpin while others treat it as a M. taeniopterus as a junior synonym of M. platycephalus.