Previously comprised of 12 species, this revision is based on examination of over 4,200 museum specimens of UlusHorn, 1870 collected throughout its range, encompassing North, Central, and South America. Lectotypes are designated for Blapstinus crassusLeConte, 1851, Ulus comatusChampion, 1893, Ulus elongatulusCasey, 1890, Ulus fimbriatusCasey, 1890, Ulus hirsutusChampion, 1885, Ulus maritimusCasey, 1890, and Ulus venezuelensisMarcuzzi, 1954 in order to clearly fix their taxonomic status. This study has revealed three new species: Ulus steineri Lumen & Smith, sp. nov. from Monahans Dunes, TX; U. paniculus Lumen & Smith, sp. nov. from Padre and Corpus Christi islands, TX; and U. guapo Lumen, Crowley, & Smith, sp. nov. from Guaymas, Sonora, MX, while at the same time uncovering variability within many taxa, resulting in seven synonomies: Ulus hirsutusChampion, 1885 (= U. elongatulussyn. nov.; = U. maritimussyn. nov.; = U. comatusChampion, 1893syn. nov.; = U. margaritensissyn. nov.; = U. venezuelensissyn. nov.); and Ulus obliquus (LeConte, 1866) (= U. fimbriatussyn. nov.; = U. latusBlaisdell, 1892syn. nov.). The fossil species Ulus minutusWhickham 1914 is placed as incertae sedis within Tenebrioninae Latreille, 1802, based on a lack of morphological data to confidently place the specimen within the tribe Opatrini Brullé, 1832, let alone the genus Ulus. A total of seven valid species are recognized in this study (U. crassus, U. guapo, U. hirsutus, U. lineatulus, U. obliquus, U. paniculus, U. steineri). Additionally, examination of female terminalia revealed all but two Ulus species (U. lineatulus and U. obliquus) possess sclerotized plates with spines in their bursa copulatrix.