The white-headed hagfish (Myxine ios) is a species of jawless fish of the family Myxinidae (hagfish).
Its scientific name alludes to the Institute of Oceanographic Sciences (IOS), Wormley, Surrey, which supplied the holotype.
Myxine ios is a marine bathydemersal fish, living at depths of . It is non-migratory, living in the North Atlantic waters off Iceland, Ireland and the western Sahara.
The white-headed hagfish may grow up to long. It is a seven-gilled hagfish; it can be distinguished from related species by its large number of tooth cusps: between 44 and 51. The Irish M. ios population is distinguished from the southern variety by its white head and whitish middorsal or midventral line.
M. ios is a scavenger of dead or disabled fish, which it bores into. Its eggs are large, .