The threadfin sculpin (Icelinus filamentosus) is a fish, mostly found in the Pacific waters of North America.

A large, deep-water sculpin of the family Cottidae, it occurs in the North Pacific Ocean, from Chirikof Island in the western Gulf of Alaska to Point Loma and Cortez Bank, southern California, USA.

The body is overall light gray, with splotches of dark brown along the upper flank and head.

The belly is light gray or yellow, and the anal fin is often a dusky color.

Its pectoral fins are quite large, roughly the size of the head.