The taxonomic treatment of Hercules beetles (subgenus Dynastes of the genus Dynastes MacLeay, 1819) is revised, with the recognition of two major species groups and 15 species. The following 10 taxa, originally designated as subspecies, have been elevated to full species status: Dynastes moroni Nagai, 2005 (REVISED STATUS); Dynastes bleuzeni Silvestre & Dechambre, 1995 (NEW STATUS); Dynastes ecuatorianus Ohaus, 1913 (NEW STATUS); Dynastes lichyi Lachaume, 1985 (NEW STATUS); Dynastes morishimai Nagai, 2002 (NEW STATUS); Dynastes occidentalis Lachaume, 1985 (NEW STATUS); Dynastes paschoali Grossi & Arnaud, 1993 (NEW STATUS); Dynastes reidi Chalumeau, 1977 (NEW STATUS); Dynastes septentrionalis Lachaume, 1985 (NEW STATUS); and Dynastes trinidadensis Chalumeau & Reid, 1995 (NEW STATUS). The use of the species name Dynastes hercules (Linnaeus, 1758) is restricted to only two island populations from Guadeloupe and Dominica. This taxonomic revision is accompanied by discussions of the basis for these taxonomic changes, i.e. based on differences in genetic, phenotypic, and ecological data and on estimates of geographic overlap. An updated Dynastes beetle phylogeny based on Illumina sequencing data is also presented for a discussion of the evolutionary relationships among the species.