Another American government creation, Super Mutants are humans that were injected with the “Forced Evolutionary Virus.”
The result is creatures that look like Frankenstein’s monster if he shaved his head and hit the gym every day twice a day.
These yoked former humans have lost a substantial amount of intelligence for all that muscle, and are generally quick to violence even if unprovoked.
There are exceptions and some slight variations on attributes depending on which region of the United States they hail from, but by and large, Super Mutant camps aren’t typically something a human vault dweller wants to encounter out in the wild.