The review of a large amount of material previously identified as the terebellid annelid, Thelepus cincinnatus (Fabricius, 1780) shows that, within European waters from the Mediterranean to the North Pole, this species should be split into four species, three of which (T. davehalli sp. n., T. marthae sp. n., and T. parapari sp. n.) are newly described here and T. cincinnatus s. str. is re-described. These four species each show distinct distribution ranges. Thelepus cincinnatus has notopodia on almost all segments and numerous eyespots; it inhabits the high boreal and arctic shelf and the North Atlantic slope, and probably also occurs on the North Pacific shelf and slope. Thelepus marthae sp. n. has no eyespots and inhabits deep waters of the high Arctic. Thelepus davehalli sp. n. has no eyespots and has notopodia on 1/2 to 2/3 of the anterior of the body; it inhabits boreal shelf waters (from Iceland to the Mediterranean) below the tidal front. Thelepus parapari sp. n. differs from the previous three species in that the uncini of the first uncinigerous segment has two teeth above the main fang; it inhabits shallow, coastal waters of the Mediterranean, inshore from the tidal front.