Idotea neglecta is a marine isopod in the family Idoteidae. It can be found on algae in the littoral and sublittoral zone of north-west European coasts.

Idotea neglecta is a marine isopod in the family Idoteidae It can be found on algae littoral sublittoral zone of north-west European coasts. I. neglecta can be found on all north-west European coasts. I. neglecta measure 8 to 30 millimetres (0.3 to 1.2 in), females 10 to 16 millimetres (0.4 to 0.6 in).

Males of I. neglecta grow up to 30 mm in length, whilst females reach 16 mm. The body of this species is relatively broad, and the pleotelson is keeled and has slightly convex, convergent sides, rounded shoulders and a single rounded point.