Galeus gracilis n.sp. (Scyliorhinidae: Pentanchinae: Galeini) is described from the uppermost slope of Western Australia and the Northern Territory. It is the second recognised member of its genus from Australian waters. This small, slender-bodied Galeus is distinguished from the 12 other species in the genus by a combination of proportional dimensions, tooth-row counts, clasper morphology, pectoral-fin radial counts, vertebral counts, intestinal valve counts, chondrocranial morphology, and colouration. It is closest to three Japanese species: G. eastmani, G. longirostris and G. nipponensis. Galeus gracilis is compared in detail to G. boardmani from southern Australia, which differs from it in numerous features.