Cyclops

The Cyclops is a species of Giant from Classical Mythology, characterized for only having a single eye set in their forehead. They were fairly unimportant figures; Cyclopses were said to be responsible for forging Zeus's thunderbolts, and it was the curse of Polyphemus, a cyclops and son of Poseidon, for his blinding that led to the famous travels of Odysseus.

Cyclopses don't have much of an important history in most fantasy games. They do show up, but they tend to be just sort of... "there". Back in the day, Advanced Dungeons & Dragons basically portrayed them as little more than "slightly tougher Ogres with only one eye", and that's more or less been their highlight.

In 4e D&D, Ogres were re-imagined with a more mystical nature; they were the Feywild equivalent of Ogres, and had magical powers, but were also highly disciplined and fanatically loyal servants of the Formians, deformed fae giants who sought to conquer the Feywild.

In Pathfinder, Ogres are the last remains of a once-mighty mystical empire that ruled through its mastery of prophecy and divination. When such magic stopped working right, they fell from power, and they are swiftly falling into decline as they devolve into barbarism. Pathfinder also features the "Great Cyclops", a rampaging brute of a cyclops based on the famous Ray Harryhausen cyclops from his 1950s film "The 7th Voyage of Sinbad".