We studied populations of frogs of the genus Atelopus from the Pasto Massif of the Andes in southern Colombia and northern Ecuador, and from the Huancabamba depression in southern Ecuador and northern Perú and conclude that they belong to six species, five of which are described as new to science. Atelopus angelito is recorded for the first time from Ecuador and its range is extended 183 km (airline) southwest of its type locality in Departamento del Cauca, Colombia. We distinguish the five new species from similar ones using features of coloration, skin texture, and morphometrics. We also include osteological data for four of the new species. A putative hybrid zone at Provincia Imbabura, Ecuador, is proposed to exist between the non-sister taxa A. ignescens and one of the new species. Because recent records of four of the new species and A. angelito are lacking despite search efforts, we hypothesize that they are possibly extinct, as are many other Andean Atelopus. Thus, we categorize these species, applying IUCN Red List criteria, as Critically Endangered (Possibly Extinct). No search efforts have been carried out for one new species (from La Victoria, Colombia); thus, it is included under the Data Deficient category. The conservation of Atelopus is briefly discussed.