Humans genetically enhanced for strength and intellect, most famously Khan Noonien Singh and his followers.
Augments are humans whose genes were deliberately engineered to improve strength, intellect and endurance. The best known arose in the late twentieth century on Earth, when genetically enhanced leaders tried to seize power during the period remembered as the Eugenics Wars.
The most famous Augment is Khan Noonien Singh, who ruled a large part of Earth before fleeing into space aboard the sleeper ship Botany Bay. Augments tend to be brilliant and physically superior, but the engineering often came with a streak of ambition and aggression that made them dangerous to ordinary people around them.
Captain Kirk and the Enterprise crew revived Khan in the episode Space Seed, and he returned in the film The Wrath of Khan with a burning desire for revenge. After the wars, the Federation banned genetic engineering of humans, and those who broke the law faced harsh consequences, as Doctor Bashir's hidden past in Deep Space Nine shows. Enterprise also touched on the subject through the stolen Augment embryos of Arik Soong.