Self-organization of defects has been widely observed in far-from-equilibrium systems and leads to the formation of ordered defect superlattice structures in materials. The formation of void or bubble superlattices has been reported in both metallic and ionic systems under different irradiation conditions, including neutron, ion, and electron irradiation. In nuclear reactor environments, the self-organization of fission products in nuclear fuels mitigates the fission-gas -release and swelling. Fundamental understanding of the underlying physics that govern the defect self-organization is essential for the prediction of lifetime of materials in nuclear reactors. In this report, we summarize our recent research on the self-organization of noble gas bubbles, solid nano-clusters, and voids in fcc and bcc metals and their stability under irradiation. The role of elastic and diffusional anisotropy on defect self-organization will be discussed.