Hollardosteus marocanus is a brachythoracid arthrodire placoderm from the Middle Devonian of Morocco. Its scrappy remains were found in Eifelian-aged strata from the Tafilat-Maider Valley.^[1]

The inferognathal plate has a well-developed anterior tooth (prong), very similar in form to the inferognathals of the dunkleosteids. However, the dermal surface of the armor is decorated with a pattern of large, crowded tubercules totally unlike the smooth dermal surfaces of dunkleosteid armors. This mix of peculiar features leaves H. marocanus placed as "Arthrodira incertae sedis,"^[1] at least until more complete specimens are found.