They are most frequently encountered in central Boston, and can also be found in Fallon's department store, Fort Strong, Trinity Tower, Revere satellite array, Big John's Salvage, The Gwinnett Restaurant and several other locations all throughout the Commonwealth, most of which can be identified by the telltale signs of hanging meat bags, twisted girders protruding out of the ground, cages and gory waste piles with which they enjoy decorating their surroundings. They are large, muscle-bound creatures with innate immunity to radiation and disease.
These mutants were created by the Institute by means of exposure to the Forced Evolutionary Virus (FEV). Institute super mutants are the variant of super mutant found throughout the Commonwealth, Nuka-World and the Island in 2287.