This chapter summarizes the main production methods of different elemental nanoparticles (NPs) from a variety of bacteria. It also includes the uniqueness of the synthesis mechanisms as well as a discussion of the morphologies of NPs. “Biomineralization” is the term used to refer to the utilization of microorganisms for the extraction of precious metals from mineral ores. The chapter contains a table that presents an overview of intracellularly biosynthesized metal NPs. Another table summarizes recent studies on extracellular bacterial NP synthesis. Many studies have been performed recently utilizing different bacteria for intracellular and extracellular bioproduction of magnetic iron oxide and iron sulfide NPs. The third table summarizes some of the reports pertaining to the synthesis of metal oxide NPs or sulfide NPs mediated by bacteria. The capability of bacteria to synthesize versatile NPs represents an effective and environmentally benign alternative to chemical and physical procedures, especially for elemental NP productions.