The genus Fornasinius was established in 1853 by Giuseppe BERTOLONI to receive a taxon that was sufficiently distinct from the known representatives of the genus Goliathus Lamarck, 1801, to merit a different placement. Here, the type species of the genus, Fornasinius fornasini Bertoloni, 1853 (type locality: Mozambique), is identified and re-described, and a male lectotype and a female paralectotype are designated from the type series. It has emerged that Fornasinius fornasini has been misidentified after its original description and that only a few specimens are known of this species. Fornasinius hauseri Kraatz, 1896, bona sp., is raised from the synonymy with Fornasinius fornasini and identified as the taxon previously referred to as Fornasinius fornasini sensu auctorum (nec BERTOLONI). Fornasinius hauseri is further split into 3 subspecies: Fornasinius hauseri sensu stricto, from south-central Kenya and possibly Cameroon; Fornasinius hauseri hirthi Preiss, 1904 stat. rev., from the Lake Victoria region and northern Tanzania; and Fornasinius hauseri bouyeri n. ssp., from south-east Democratic Republic of the Congo (former Katanga Province). A new species, Fornasinius polydorus n. sp. is described from Nakuru National Park in central Kenya.