Helios was imagined as a handsome god crowned with the shining aureole of the sun, who drove the chariot of the sun across the sky each day to earth-circling Oceanus and through the world-ocean returned to the East at night. Homer described Helios's chariot as drawn by solar bulls (Iliad xvi.779); later Pindar described it as drawn by "fire-darting steeds" (Olympian Ode 7.71). Still later, the horses were given fiery names: Pyrios, Aeos, Aethon, and Phlegon.
Helios was sometimes referred to with the epithet Helios Panoptes ("the all-seeing"). In the story told in the hall of Alcinous in the Odyssey (viii.300ff), Aphrodite, the consort of Hephaestus secretly beds Ares, but all-seeing Helios spies on them and tells Hephaestus, who ensnares the two lovers in nets invisibly fine, to punish them.
Though Odysseus warns his men not to, they impiously kill and eat some of the cattle of the Sun. The guardians of the island, Helios' daughters, tell their father, and Helios appeals to Zeus, who destroys the ship and kills all the men except for Odysseus.
In one Greek vase painting, Helios appears riding across the sea in the cup of the Delphic tripod which appears to be a solar reference. Athenaeus in Deipnosophistae relates that, at the hour of sunset, Helios climbed into a great golden cup in which he passes from the Hesperides in the farthest west to the land of the Ethiops, with whom he passes the dark hours. While Heracles traveled to Erytheia to retrieve the cattle of Geryon, he crossed the Libyan desert and was so frustrated at the heat that he shot an arrow at Helios, the sun. Helios begged him to stop and Heracles demanded the golden cup which Helios used to sail across the sea every night, from the west to the east. Heracles used this golden cup to reach Erytheia.
Helios is sometimes identified with Apollo; "Different names may refer to the same being," Walter Burkert observes, "or else they may be consciously equated, as in the case of Apollo and Helios.
The earliest certain reference to Apollo identified with Helios appears in the surviving fragments of Euripides' play Phaethon in a speech near the end (fr 781 N²), Clymene, Phaethon's mother, laments that Helios has destroyed her child, that Helios whom men rightly call Apollo (the name Apollo is here understood to mean Apollon "Destroyer").
By Hellenistic times Apollo had become closely connected with the sun in cult. His epithet Phoebus "shining", drawn from Helios, was later also applied by Latin poets to the sun-god Sol. The identification became a commonplace in philosophic texts and appears in the writing of Parmenides, Empedocles, Plutarch and Crates of Thebes among others, as well as appearing in some Orphic texts. Pseudo-Eratosthenes writes about Orpheus in Catasterismi, section 24:
Dionysus and Asclepius are sometimes also identified with this Apollo Helios.
Classical Latin poets also used Phoebus as a byname for the sun-god, whence come common references in later European poetry to Phoebus and his car ("chariot") as a metaphor for the sun. But in particular instances in myth, Apollo and Helios are distinct. The sun-god, the son of Hyperion, with his sun chariot, though often called Phoebus ("shining") is not called Apollo except in purposeful non-traditional identifications. Roman poets often referred to the sun god as Titan.
Despite these identifications, Apollo was never actually described by the Greek poets driving the chariot of the sun. Therefore, Helios is still known as the 'sun god' - the one who drives the sun chariot across the sky each day.
"The island of Rhodes is almost the only place where Helios enjoys an important cult", Burkert asserts (p 174), instancing a spectacular rite in which a quadriga, a chariot drawn by four horses, is driven over a precipice into the sea, with its overtones of the plight of Phaethon noted. There annual gymnastic tournaments were held in his honor. The Colossus of Rhodes was dedicated to him. Helios also had a significant cult on the acropolis of Corinth on the Greek mainland.
The tension between the mainstream traditional religious veneration of Helios, which had become enriched with ethical values and poetical symbolism in Pindar, Aeschylus and Sophocles, and the Ionian proto-scientific examination of Helios the Sun, a phenomenon of the study Greeks termed meteora, clashed in the trial of Anaxagoras ca 450 BCE, a forerunner of the culturally traumatic trial of Socrates for irreligion, in 399.