In Homer, Iliad 23.665 he is the father of Epeus, maker of the wooden horse.
According to Pausanias 2.29.2, Panopeus -- or, more authetically, Phanoteus (cf. phi 80) -- was the son of Phokos, after whom the area around Mt. Parnassos was called Phokis.
Panopeus gave his name to one of the cities, which Pausanias calls "a polis of the Phocians, if one can give the name of polis to those who possess no government offices, no gymnasium, no theater, no market-place, no water descending to a fountain, but live in bare shelters just like mountain cabins, right on a ravine" (10.4.1). This passage has become a locus classicus in modern attempts (from M.I. Finley onwards) to identify the defining criteria of the polis: see bibliography and discussion in S.E.Alcock, 'Pausanias and the polis', in M.H. Hansen (ed.) Sources for the Ancient Greek City-State, Acts of the Copenhagen Polis Centre 2 (Copenhagen 1995) 326-344, at 326-327; and J. Ouhlen, 'Phanoteus, Panopeus', in M.H. Hansen and T.H. Nielsen (eds.), An Inventory of Archaic and Classical Poleis (Oxford 2004) 424-425.