The Odyssey (Greek: Ὀδύσσεια, Odýsseia) is one of two major ancient Greek epic poems attributed to Homer. It is, in part, a sequel to the Iliad, the other work traditionally ascribed to Homer. The poem is fundamental to the modern Western canon. Indeed it is the second—the Iliad being the first—extant work of Western literature. It was probably composed near the end of the eighth century BC, somewhere in Ionia, the Greek-speaking coastal region of what is now Turkey.

The poem mainly centers on the Greek hero Odysseus (or Ulysses, as he was known in Roman myths) and his long journey home following the fall of Troy. It takes Odysseus ten years to reach Ithaca after the ten-year Trojan War. In his absence, it is assumed he has died, and his wife Penelope and son Telemachus must deal with a group of unruly suitors, the Mnesteres (Greek: Μνηστῆρες) or Proci, competing for Penelope's hand in marriage.

It continues to be read in the Homeric Greek and translated into modern languages around the world. The original poem was composed in an oral tradition by an aoidos (epic poet/singer), perhaps a rhapsode (professional performer), and was intended more to be sung than read. The details of the ancient oral performance, and the story's conversion to a written work inspire continual debate among scholars. The Odyssey was written in a regionless poetic dialect of Greek and comprises 12,110 lines of dactylic hexameter. Among the most impressive elements of the text are its strikingly modern non-linear plot, and that events seem to depend as much on the choices made by women and serfs as on the actions of fighting men. In the English language as well as many others, the word odyssey has come to refer to an epic voyage.