Soft coral diversity in tropical northern Australia remains relatively understudied compared with other parts of the world. As a result of ongoing biodiversity surveys, we describe here a new genus of Octocorallia, Anastromvos, gen. nov., and two new species, A. aldersladei, sp. nov. and A. catherinae, sp. nov., collected from waters off the Pilbara, Kimberley and Darwin. To test the validity of the new genus, we used traditional morphological approaches combined with a molecular phylogeny using three mitochondrial genes (COI, mtMutS, ND2) and nuclear 28S. The markers did not amplify for the colony of A. catherinae, sp. nov., which was described on the basis of morphology only. The new genus, belonging to the family Alcyoniidae, is dimorphic, possessing autozooids and siphonozooids, and is characterised by its unique capitate growth form, stone-like colony consistency, heavy autozooid polyp armature and the possession of clubs, tuberculated spindles and/or oval-shaped sclerites and crosses. The molecular phylogeny shows the new genus as the sister group to Sarcophyton + Lobophytum, and forms a unique clade among other alcyoniid clades. The Sarcophyton–Lobophytum group of taxa can be ecologically dominant in shallow-water coral reef communities but there is still much taxonomic refinement needed for these and related genera.