Thrombolite and stromatolite reefs occur at several stratigraphic levels within the terminal Proterozoic Nama Group of central and southern Namibia. The reefs form integral parts of several carbonate platforms within the Nama Group, including the Kuibis platform of the northern Nama Basin (Zaris subbasin) and Huns platform (Witputs subbasin) of the southern Nama Basin. The reefs are composed of both thrombolites (clotted internal texture) and stromatolites (laminated internal texture) that form laterally continuous biostromes, isolated patch reefs and isolated pinnacle reefs ranging in scale from a meter to several kilometers in width. In the majority of cases, the reefs occur stratigraphically as an integral facies within the Transgressive System Tracts of sequences making up the Kuibis and Huns platforms. This suggests that a regime of increasing accommodation was required to form well developed reefs, though reefs occur sporadically in Highstand Systems Tract settings. Within a given TST, a regime of increasing accommodation in time favors the transition from sheet-like biostromal geometries to more isolated patch and pinnacle biohermal geometries. Similarly, increasing accommodation space, such as a transect down depositional dip, shows a similar transition from more sheet-like geometries in updip positions to more isolated geometries in downdip positions. Reefal facies consist of thrombolitic domes, columns and mounds with well developed internal clotted textures, in addition to stromatolitic domes, columns and mounds, with crudely to moderately well developed internal lamination. Stromatolites are better developed in conditions of relatively low accommodation, updip locations under conditions of higher current velocities and greater sediment influx. Thrombolites are better developed in conditions of relatively high accommodation and low sediment influx. Both types of microbialites are intimately associated with the first calcifying metazoan organisms which may have attached themselves or otherwise lived within sheltered depressions within the rough topography created by ecologically complex mats. The appearance of thrombolitic textures during terminal Proterozoic time is consistent with the hypothesis of Feldman and McKenzie (1998) that colonization of cyanobacterial mats by higher algae and metazoans was an important process in generating clotted textures. Fabrics in the Nama thrombolites are well preserved and show evidence of thrombolitic mesoclots being overgrown by fibrous marine calcite, interpreted as former aragonite. This was followed by emplacement of geopetal micrite fills, precipitation of primary dolomite as an isopachous rim cement, followed by occlusion of remaining porosity by blocky calcite spar.