Helios was one of the Titans, son of Hyperion and Theia. He was the personification of the Sun and his sisters were the goddesses Selene (the Moon) and Eos (the Dawn). He drove the chariot of the sun across the sky on a daily basis. In later times, Helios was considered being the god of light, Apollo, although sometimes they would still be thought of as distinct deities; after all, Helios was a Titan, while Apollo was an Olympian.
Helios did not play a major part in Greek mythology, as he was eventually replaced by Apollo. However, one of the best known stories around Helios revolves around his son Phaeton, who tried to drive his father's chariot; nevertheless, he lost control and set the earth on fire.