Large-scale, heterogeneous peer-to-peer (P2P) systems impose a set of diverse requirements. Current solutions do commonly only address a subset of these requirements since there are a number of trade-offs and constraints due to the different dimensions and aims they address. We present a novel approach for designing overlay networks for large-scale, highly dynamic, and heterogeneous P2P systems. A set of mechanisms is proposed to meet the complete set of requirements while keeping the trade-offs and constraints in balance. To handle effectively the large number of peers, they are clustered in manageable groups considering the requirements on their stability. The novelty in this approach is in the identification of the core services and operations of the aforementioned systems. On the basis of the requirements of those services and operations, peers are assigned the most suitable roles. Role relationships are further introduced to enable (and provide) incentives for the peers to adopt the most suitable roles while selecting an efficient overlay structure to preserve efficiency, robustness, and scalability. The proposed set of mechanisms is realized in Omicron, a novel hybrid P2P approach.