Hyperion is the Titan personification of light and he is often also seen as the personification of the sun. “But wait”, we hear you say, “I thought that Helios was the personification of the sun already?”. Well, that is Greek mythology for you. Sometimes two gods and/or Titans represent the same concept. It works because polytheism.
Hyperion is a son of Uranus and Gaia. He has married his sister Tethys, with whom he brought forth offspring that would carry on his legacy: Helios (the sun), Selene (the moon), and Eos (the dawn). Hyperion moved the sun and the moon to create the cycle of days. So basically, he told his kids where to go at what moment in time.
He fought on the side of the Titans during the war with the Olympians. When the Titans were defeated, he was locked away in the pits of Tartarus.