According to the Greek poet Hesiod, Helios was the son of two Titans - Theia and Hyperion. In Hesiod's Theogony, therefore, Helios was also the brother of Eos (the goddess of Dawn) and Selene (the goddess of the Moon). It is interesting to note that the Dawn goddess Eos began the procession of morning, followed closely by her brother Helios.
There are several myths in which Helios plays a part. One of the most memorable of these tales is the legend of Phaethon. The Sun god also appears in the sad story of the ill-fated nymph Clytie. However, Helios is at his best as a sort of heavenly spy, from whom not much can be kept secret. In the Homeric Hymn to Demeter, the goddess Demeter asks Helios for assistance in locating her daughter Persephone. Likewise, it is the Sun god who first notices the affair that is taking place between the Olympians Aphrodite and Ares in the Odyssey.
Helios was also the father to some important mythical characters. With his wife, the Oceanid Perseis, Helios had three legendary children - Circe, Pasiphae, and Aeetes (incidentally, the couple had a number of other, less illustrious, children). The god also had numerous relationships with women that resulted in the birth of offspring. The aforementioned Phaethon, for example, was the product of such a union. These "children of the Sun" were sometimes referred to as Heliades in Greek mythology and literature.
Helios was known by the name Sol in Roman mythology.
Who's Who in Classical Mythology