This book outlines the design, modeling and analysis of freestanding, spherical and cuboid-shaped composite plasmonic nanostructures exhibiting tailorable exotic plasmon-enhanced optical phenomena such as ultra-narrowband scattering, ultra-sensitive sensing, and ultra-wideband absorption. It provides a brief introduction to this exciting scientific field, discusses pertinent analytical and computational methods commonly used to design plasmonic nanosystems, and presents a range of design methodologies including theoretical and simulation models, along with their experimental realizations for most of the cases. As such, this multifunctional book caters to the needs of both newcomers and researchers interested in developing novel plasmonic systems with applications in this multidisciplinary area of modern optics, electronics, and materials engineering.