Prometheus is a Titan in the Greek pantheon, the son of Iapetus. Prometheus is perhaps best known as the greatest friend to humanity among the gods.
Prometheus provided a choice of two offerings to Zeus: fine meat hidden inside an unappetizing ox's stomach, and bones wrapped in edible fats. Zeus was tricked by the appearance and chose the offering containing the bones. This set the bar for future offerings from the Greeks, who would enjoy the meat from their sacrifices and burn the bones and fats for the gods.
Zeus, of course, was angered by this and withheld fire from humanity, which Prometheus stole back and returned to them.
Zeus' answer to the theft of fire was to send Pandora to mankind. He punished Prometheus more directly, however, chaining him to a rock. For all of eternity, Prometheus would remain there while each day, an eagle would land and devour his liver. Each night, due to his divine status, Prometheus' liver would grow back, and the process would begin again. This repeated agony is not unlike that endured by Sisyphus during his punishment.
In the myths, Prometheus is eventually saved by Heracles, who shot and killed the eagle, ending Prometheus' torment.