Although the Caribbean region is recognized as a major biodiversity hotspot, many megadiverse groups remain taxonomically understudied. The ornate spiders of the genus Spintharus Hentz, 1850 (Theridiidae, Araneae) are a good example where taxonomic boundaries have remained unclear. The genus shows profuse habitus and genitalic variation in the Caribbean and has distinct colour patterns that rapidly degrade in ethanol. The leading theridiid taxonomist of the last six decades (Herbert W. Levi) therefore concluded that the morphological diversity of Caribbean Spintharus was, with the evidence available at the time, best characterized as intraspecific variation. The first molecular study, however, rejected the 'single widespread species' hypothesis, rather indicating multiple short-range endemics. This paper describes and diagnoses 15 new species based on the combination of molecular and morphological data, including S. davidattenboroughi sp. nov., S. barackobamai sp. nov., S. michelleobamaae sp. nov., S. davidbowiei sp. nov., S. leonardodicaprioi sp. nov. and S. berniesandersi sp. nov. Much Caribbean diversity may be similarly 'hidden' by existing taxonomical hypotheses; clearly, more focus is needed on the taxonomy of megadiverse groups. The implications of integrated taxonomy dramatically alter conservation biology when a single widespread species is instead found to represent multiple short-range endemics. Our goal here is thus to update Spintharus taxonomy and discuss the implications of the newly found diversity for both biodiversity research and conservation.