Humans -- Common humanoid species, sometimes called "Smoothskins" by Ghouls and "Normals" by Super Mutants. Due to direct exposure to radiation and exposition of the FEV of the West Tek Facility, Humans who have lived in the wasteland, unprotected by the Vaults, have exhibit more diversity, primarily in genetic structure. These mutations are non-lethal, non-damaging variantions in the Human DNA that simply increase the genepool variety. Minor mutations may erupt like additional toes, loss of hair, and permanent red eyes.
Human Psykers -- Humans who possess paranormal powers due to mutations. These Humans have identical or near-identical phenotypes as many Humans but many of their senses have evolved. Subgroups of Human Psykers include the Beastlords (Humans who have developed psychic control over animals) and the Slags (Humans who physiology adapted to prolonged seclusion underground, possessing perfect dark light-vision.
Deformities -- Humans who have experienced an exceptional amount of phyiscal altercations from radiation alone. Dwarves are Humans with dwarfism because of radiation, which has drastically reduced their stature. Swampfolk are Humans who have experienced great deformities as a result of the New Plague infection, ionizing radiaiton, and inbreeding. They've grown misshapen limbs and vastly different anatomy. Trogs are hairless primate-like, frog-shaped Human mutants infected by the Troglodyte Degeneration Contagion.
Ghouls -- Humans with a unique genetic makeup that have evolved by heavy radiation poisoning which erodes their skin and greatly extends their life. They are sterile and immune to the lethal effects of radiation but not is degenerative effects.
Feral Ghouls -- Ghouls without the regenerative ability of the neurological system that affords their longetivity into the higher reasoning functions of the brain itself, causing them to lose their ability to reason and become hostile towards all non-ghouls.
Glowing Ones -- Ghouls who have absorbed an unusually high amount of radiation into their bloodstreams and muscle tissue without their neurological systems filtering these particles, becoming luminescent yellow-green living conduits of radiation.
Super Mutants -- Taller, bulkier, and muscular Human mutants, gifted with superhuman strength and endurance, and resistances to radiation and poison.
Nightkin -- Blue pale Super Mutants who have the ability to turn invisible because of prolonged effects of Stealth Boy use.