Penion lineatus is a species of medium-sized marine snail or whelk, belonging to the true whelk family Austrosiphonidae. It was described in 2018.
Adult shells are between 68 mm and 172 mm in length. The shell protoconch is cream coloured and the teleoconch is covered in yellow or brown bands.
Penion lineatus is endemic to waters surrounding the Three Kings Islands and Cape Reinga north of mainland New Zealand. Since the species has a naturally restricted geographic range, its conservation status within the New Zealand Threat Classification System has been categorised as at risk and naturally uncommon by the Department of Conservation.