The genus Eresus Walckenaer, 1805 includes some of the world’s most charismatic spiders; however, its taxonomy requires considerable improvement. Not only are morphological studies lagging behind, but the molecular exploration of the genus is still in its infancy. This is especially true for the Caucasian, Middle Eastern, and East Asian faunas. In this study, we describe seven new Eresus species from Iran based on males. We also provide new illustrations of E. hermani Kovács et al., 2015 based on both male paratypes and of E. sandaliatus (Martini and Goeze, 1778) based on specimens from the Netherlands. Previous records of the genus in Iran are also re-evaluated. In total, we generated 18 new DNA barcodes (representing 16 species), and performed phylogenetic analyses for 33 sequences. We also performed species’ delimitation analyses for these sequences recovering 24 species. The phylogeny revealed six distinct maternal lineages, three of which we recognize formally as species groups. The newly described taxa reveal high species’ diversity in Iran, bringing the total to eight species. Based on our preliminary results, we see the eastern Caucasus as a potential refugium for the sandaliatus species group of the genus.