In this perspective the numerous applications of polyphenylene dendrimers as nano materials with site defined functionalities are presented. All selected examples emphasize which dendrimer characteristics were exploited for different purposes in order to help identifying new and yet unforeseen future applications. While polyphenylene dendrimers were first used as precursors for graphene molecules, their stiff and monodisperse nature quickly established their utilization in various new fields. Their rigid and bulky structure has been used for the encapsulation of conjugated polymers, chromophores and catalysts to prevent aggregation and for creating highly shielded and large weakly coordinating ions. The site specificity of the rigid scaffold has been utilized to design multichromophores from different, specifically placed dyes for controlled energy transfer and for the synthesis of surface functionalized organic nanoparticles with well defined sizes. Supramolecular structures formed by polyphenylene dendrimers such as fibers, rods and hybrid nanoparticle networks have been studied and their application as precursors and templates has been explored. The interior hydrophobic voids of polyphenylene dendrimers have been functionalized with hydrophilic or metal coordinating moieties and their applicability for host–guest chemistry and chemical sensing has been demonstrated.