Limax luctuosus is a species of air-breathing land slug, a terrestrial pulmonate gastropod mollusk in the family Limacidae, the keelback slugs.
The taxon was first described by Alfred Moquin-Tandon in 1855 as a variety of Limax maximus. It could be a form of Limax cinereoniger or an endemic species.
Limax luctuosus was described from France, but it should also be present in the western Alps.