The Assassin Spiders of the family Archaeidae are an ancient and iconic lineage of basal araneomorph spiders, characterised by a specialised araneophagic ecology and unique, 'pelican-like' cephalic morphology. Found throughout the rainforests, wet sclerophyll forests and mesic heathlands of south-western, south-eastern and north-eastern Australia, the genus Austrarchaea Forster & Platnick, 1984 includes a diverse assemblage of relictual, largely short-range endemic species. With recent dedicated field surveys and significant advances in our understanding of archaeid biology and ecology, numerous new species of assassin spiders have been discovered in the montane sub-tropical and warm-temperate closed forests of mid-eastern Australia, including several rare or enigmatic taxa and species of conservation concern. This fauna is revised and 17 new species are described from south-eastern Queensland and eastern New South Wales: Austrarchaea alanisp. n., Austrarchaea aleenaesp. n., Austrarchaea binfordaesp. n., Austrarchaea christopherisp. n., Austrarchaea clyneaesp. n., Austrarchaea cunninghamisp. n., Austrarchaea dianneaesp. n., Austrarchaea harmsisp. n., Austrarchaea helenaesp. n., Austrarchaea judyaesp. n., Austrarchaea mascordisp. n., Austrarchaea mcguiganaesp. n., Austrarchaea milledgeisp. n., Austrarchaea monteithisp. n., Austrarchaea platnickorumsp. n., Austrarchaea ravenisp. n. and Austrarchaea smithaesp. n. Adult specimens of the type species, Austrarchaea nodosa (Forster, 1956) are redescribed from the Lamington Plateau, south-eastern Queensland, and distinguished from the sympatric species Austrarchaea dianneaesp. n. A key to species and a molecular phylogenetic analysis of COI and COII mtDNA sequences complement the species-level taxonomy, with maps, habitat photos, natural history information and conservation assessments provided for all species.