The Sibylline Oracles (Latin: Oracula Sibyllina) are a collection of oracular utterances written in Greek hexameters ascribed to the Sibyls, prophetesses who uttered divine revelations in a frenzied state. Fourteen books and eight fragments of Sibylline Oracles survive, in an edition of the 6th or 7th century AD. They are not to be confused with the original Sibylline Books of the ancient Etruscans and Romans which were burned by order of the Roman general Flavius Stilicho in the 4th century AD. Instead, the text is an "odd pastiche" of Hellenistic and Roman mythology interspersed with Jewish, Gnostic and early Christian legend.

The Sibylline Oracles are a valuable source for information about classical mythology and early first millennium Gnostic, Hellenistic Jewish and Christian beliefs. Some apocalyptic passages scattered throughout seem to foreshadow themes of the Book of Revelation and other apocalyptic literature. The oracles have undergone extensive editing, re-writing, and redaction as they came to be exploited in wider circles.

One passage has an acrostic, spelling out a Christian code-phrase with the first letters of successive lines.

The Sibylline Oracles in their existing form are a chaotic medley. They consist of 12 books (or 14) of various authorship, date, and religious conception. The final arrangement, thought to be due to an unknown editor of the 6th century AD (Alexandre), does not determine identity of authorship, time, or religious belief; many of the books are merely arbitrary groupings of unrelated fragments.

These oracles were anonymous in origin and as such were apt to modification and enlargement at pleasure by Hellenistic Jews and by Christians for missionary purposes. Celsus called Christians Σιβυλλισται ('sibyl-mongers' or 'believers in sibyls') because of prophecies preached among them, especially those in the book of Revelation. The preservation of the entire collection is due to Christian writers.

The oldest of the surviving Sibylline oracles seem to be books 3–5, which were composed partly by Jews in Alexandria. The third oracle seems to have been composed in the reign of Ptolemy VI Philometor. Books 1–2 may have been written by Christians, though again there may have been a Jewish original that was adapted to Christian purposes.

All the oracles seem to have undergone later revision, enrichment, and adaptation by editors and authors of different religions, who added similar texts, all in the interests of their respective religions. The Sibylline oracles are therefore a pastiche of Greek and Roman pagan mythology, employing motifs of Homer and Hesiod; Judeo-Christian legends such as the Garden of Eden, Noah and the Tower of Babel; Gnostic and early Christian homilies and eschatological writings; thinly veiled references to historical figures such as Alexander the Great and Cleopatra, as well as many allusions to the events of the later Roman Empire, often portraying Rome in a negative light.

Some have suggested that the surviving texts may include some fragments or remnants of the Sibylline Books with a legendary provenance from the Cumaean Sibyl, which had been kept in temples in Rome. The original oracular books, kept in Rome, were accidentally destroyed in a fire in 83 BC, which resulted in an attempt in 76 BC to recollect them when the Roman senate sent envoys throughout the world to discover copies. This official copy existed until at least AD 405, but little is known of their contents.