Severe high pressure, high temperature downhole environment in gas and oil industry, and high dose radiation in nuclear reactors posed significant challenges for the application of metallic materials. In this paper, we will review our recent discovery of nanostructured triphase metallic materials that have extraordinary high temperature thermal stability. These nanostructured metallic materials also have high mechanical strength than their coarse grained counterparts. Metallic multilayers with immiscible layer interface also have the potential for accomplishment of high temperature thermal stability. Furthermore these immiscible multilayers have extraordinary radiation resistance. By using in situ radiation experiments inside a transmission electron microscope, we show that nanostructured multilayers have exceptional radiation tolerance with capability to remove radiation induced dislocation loops. Advanced materials are clearly necessary for their application in various extreme environments. Under this context, nanostructured metallic materials metals have emerged as promising candidates with superior damage tolerance. The rapid development of numerous energy sectors calls for the design of advanced materials. Taking gas and oil industry as an example, the continuous push towards high temperature and high pressure downhole environment put increasing challenges to sustainability of currently employed metallic materials. In parallel, next generation nuclear reactors are being and designed to provide increasing service lifetime and enhanced safety and reliability. Materials to be employed to construct these reactors needs to withhold higher temperature, much aggressive radiation dose and in many cases corrosive environment. The properties of traditional metallic materials cannot accommodate these requirements. Extensive studies are being performed to search for novel metallic materials with unprecedented advanced properties. In this paper, we will discuss strategies to enhance thermal stability and radiation tolerance of metallic materials. Two examples will be provided to illustrate the ideas.