Heavy metal is a classification of elements, typically metallic, characterized by high atomic mass or density. Within nuclear physics and energy research, this concept designates elements whose isotopes are studied for their significant nuclear properties, such as fission cross-sections, complex decay schemes, and behavior in nuclear environments. Research in this domain investigates their nuclear structure, reaction dynamics, radiochemistry, and material properties, providing fundamental insights crucial for nuclear energy generation, radioactive waste management, and the understanding of astrophysical processes.