One new calcareous nannofossil genus Senilatus; four new calcareous nannofossil species Calculites favosus, Lithraphidites? charactozorro Self-Trail and Pospichal, Rucinolithus oriens, and Watznaueria bybelliae; and one new combination, Senilatus zipperum n. gen. and comb., are described from Upper Cretaceous (upper Campanian to Maastrichtian) sediments of east-central South Carolina. These new species were described from five coreholes located in marine coastal plain deposits. There is evidence that the presence of one species, Senilatus zipperum, is indicative of nearshore, restricted environments. Scanning electron and light microscope pictures are provided for two species, Cretarhabdus multicavus Bukry, 1969 and Retemediaformis teneraretis Varol, 1991, that have previously been documented only with the transmission electron microscope. The ranges of these two species have been extended beyond those stated in the original descriptions.