The historicity of Orpheus was generally accepted by the ancients, though Aristotle believed that he never actually existed. He is not mentioned in Homer or Hesiod. The earliest surviving reference is a two-word fragment of the sixth-century B.C. lyric poet Ibycus: onomaklyton Orphēn ("Orpheus famous of name").

Orpheus was called by Pindar "the father of songs" and asserted to be a son of the Thracian river god Oeagrus. The Muse Calliope was his mother, but as Karl Kerenyi observes, "in the popular mind he was more closely linked to the community of his disciples and adherents than with any particular race or family".

The Greeks of the Classical age venerated the legendary figure of Orpheus as chief among poets and musicians, and the perfecter of the lyre invented by Hermes. Poets like Simonides of Ceos said that, with his music and singing, he could charm birds, fish and wild beasts, coax the trees and rocks into dance, and even divert the course of rivers. He was one of the handful of Greek heroes to visit the Underworld and return; even to Hades his song and lyre did not lose their power.

As one of the pioneers of civilization, he is said at various times to have taught humanity the arts of medicine, writing (in one unusual instance, where he substitutes for the usual candidate, Cadmus) and agriculture, where he assumes the Eleusinian role of Triptolemus. More consistently and more closely connected with religious life, Orpheus was an augur and seer; practiced magical arts, especially astrology; founded or rendered accessible many important cults, such as those of Apollo and the Greek god Dionysus; instituted mystic rites both public and private; and prescribed initiatory and purificatory rituals, which his community of followers treasured in Orphic texts. In addition, Pindar and Apollonius of Rhodes place Orpheus as the harpist and companion of Jason and the Argonauts. Orpheus had a brother named Linus that went to Thebes and became a Theban.

Several etymologies for the name Orpheus have been proposed. A probable suggestion is that it is derived from a hypothetical PIE verb *orbhao-, "to be deprived", from PIE *orbh-, "to put asunder, separate". Cognates would include Greek orphe, "darkness", and Greek orphanos, "fatherless, orphan", from which comes English "orphan" by way of Latin. Orpheus would therefore be semantically close to goao, "to lament, sing wildly, cast a spell", uniting his seemingly disparate roles as disappointed lover, transgressive musician and mystery-priest into a single lexical whole. The word "orphic" is defined as mystic, fascinating and entrancing, and, probably, because of the oracle of Orpheus, "orphic" can also signify "oracular". Fulgentius, a mythographer of the late 5th to early 6th century AD, gave the unlikely etymology meaning "best voice" , "Oraia-phonos".

Strabo (64 BC – ca. AD 24) surprisingly gives a more mundane telling of Orpheus's life, presenting him as a mortal, though he mentions that he was a "wizard" who lived and died in a village close to Olympus. He writes that he practiced his skill for money but later gathered followers and power that in the end killed him. He uses the word agurteuonta (αγυρτεύοντα), a term used by Sophocles in Oedipus Tyrannus to characterize Teiresias as a trickster with an excessive desire for possessions. The word agurtēs (αγύρτης) most often meant charlatan and always had a negative connotation.

Pausanias wrote of an Egyptian who also had the opinion that Orpheus was a magician, using the word mageuse (μάγευσε).

According to Apollodorus and a fragment of Pindar, Orpheus's father was Oeagrus, a Thracian king; or, according to another version of the story, the god Apollo. His mother was the muse Calliope; or, a daughter of Pierus, son of Makednos. His birthplace and place of residence was in Pimpleia, Olympus. In Argonautica the location of Oeagrus and Calliope's wedding is close to Pimpleia, near Olympus. While living with his mother and her eight beautiful sisters in Parnassus, he met Apollo, who was courting the laughing muse Thalia. Apollo became fond of Orpheus and gave him a little golden lyre and taught him to play it. Orpheus's mother taught him to make verses for singing. Strabo mentions that he lived in Pimpleia. He is also said to have studied in Egypt.

Orpheus is said to have established the worship of Hecate in Aegina. In Laconia Orpheus is said to have brought the worship of Demeter Chthonia and that of the Kores Sōteiras (Greek,Κόρες Σωτείρας) savior maid.[clarification needed] Also in Taygetus a wooden image of Orpheus was said to have been kept by Pelasgians in the sanctuary of the Eleusinian Demeter.

The Argonautica (Greek: Ἀργοναυτικά) is a Greek epic poem written by Apollonius Rhodius in the 3rd century BC. Orpheus took part in this adventure and used his skills to aid his companions. Chiron told Jason that without the aid of Orpheus, the Argonauts would never be able to pass the Sirens—the same Sirens encountered by Odysseus in Homer's epic poem the Odyssey. The Sirens lived on three small, rocky islands called Sirenum scopuli and sang beautiful songs that enticed sailors to come to them, which resulted in the crashing of their ship into the islands. When Orpheus heard their voices, he drew his lyre and played music that was more beautiful and louder, drowning out the Sirens' bewitching songs.