One of our best ancient sources for information about mythology is the Greek poet Hesiod. Hesiod's poems, which include the Theogony, Works and Days, and the Shield, each reveal a great deal about the mythological figures that so occupied the imaginations of Greek writers, poets, and artists. Furthermore, Hesiod has left us a remarkable record of the legendary birth of many of the Greek gods and goddesses in his Theogony. And so it is to the Theogony that we turn for stories of Hyperion.
According to Hesiod, Hyperion was the son of two important divine beings. These powerful gods were called Gaia and Ouranos, and they represented the Earth (Gaia) and the Sky (Ouranos). Together, Gaia and Ouranos had many children, and the poet Hesiod seems to delight in listing the names of their sons and daughters in his Theogony. Here is a relevant passage from that work:
"But then she [Gaia] did couple with Ouranos
to bear deep-eddying Okeanos,
Koios and Kreios, Hyperion and Iapetos,
Theia and Rheia, Themis and Mnemosyne,
as well as gold-wreathed Phoebe and lovely Tethys."
(Hesiod, Theogony, 132-136)
"Theia yielded to Hyperion's love and gave birth
to great Helios and bright Selene and Eos,
who brings light to all the mortals of this earth
and to the immortal gods who rule the wide sky."
(Hesiod, Theogony, 371-374)
In Greek mythology, Helios was the god of the Sun, Eos the goddess of Dawn, and Selene the goddess of the Moon. So these children of Hyperion each represent light. It is also worth noting that Hyperion is sometimes conflated with his son - the Sun - Helios in myth and literature.
Who's Who in Classical Mythology