Cyclops (Ancient Greek: Κύκλωψ, romanized: Kúklōps) is an ancient Greek satyr play by Euripides, based closely on an episode from the Odyssey. It is likely to have been the fourth part of a tetralogy presented by Euripides in a dramatic festival in 5th-century BC Athens, although its intended and actual performance contexts are unknown. The date of its composition is unknown, but it was probably written late in Euripides' career. Richard Seaford believes that it could have been written as early as 424 BC, but it is more often dated to around 408 BC. It is the only complete satyr play extant.

The play is set in Sicily at Mount Aetna. It begins with an opening monologue by Silenus, who tells the tale of how he and the satyrs (who are his offspring and followers) have been abused by the giant Cyclops (named by him as Polyphemus (l. 25)). The satyrs are now enslaved to work for the Cyclops, and shepherd his flock (ll. 1–85). Odysseus, who has lost his way on the voyage home from the Trojan War, arrives with his hungry sailors. They meet Silenus and offer to trade wine for food. Being a servant of Dionysus, Silenus cannot resist obtaining the wine despite the fact that the food is not his to trade. But the Cyclops soon arrives and Silenus is quick to accuse Odysseus of stealing the food (ll. 86–275).

Odysseus has a lively debate with the Cyclops, arguing against his brutality, and in favor of morality, law, justice and hospitality, while the Cyclops argues in support of personal advantage and pleasure. The Cyclops considers the idea of social justice a fraud created by the weak as protection against the mighty; he is basically an atheist (ἀνόσιος, anosios, impious), and claims that the only thing worthy of worship is wealth. After this debate, the Cyclops brings Odysseus and his crew inside his cave and eats two of them. Odysseus manages to sneak out, stunned by what he has witnessed. In revenge, he plans a scheme to get the Cyclops drunk and blind him with a burning stake after the giant has passed out from inebriation (ll. 276–515).

The Cyclops and Silenus drink together, with Silenus attempting to hoard the wineskin for himself. When the Cyclops is drunk, he says he sees the gods, and begins to call Silenus his Ganymede (the beautiful prince whom Zeus made his immortal cup bearer and lover). The Cyclops then steals Silenus away into his cave, explaining that he takes "more pleasure in boys than in women" ("τοῖς παιδικοῖσι μᾶλλον ἢ τοῖς θήλεσιν", tois paidikoisi māllon ē tois thēlesin [l. 584]). Odysseus now decides to execute the next phase of his plan. The satyrs initially agreed to help, but later offer a variety of absurd excuses when the time for action comes. The annoyed Odysseus gets his crew to help instead and they blind the Cyclops (ll. 516–660).

As Odysseus had told the Cyclops earlier that his name was "Nobody" (οὔτις, outis), when the Cyclops screams who was responsible for blinding him, it sounds like he is saying that nothing is wrong ("Nobody blinded me", Οὖτίς με τυφλοῖ βλέφαρον, Outis me tuphloi blepharon [l. 673]), and the satyrs mock him over this. Once Odysseus and his men have escaped the cave, he reveals his true name and sets off, taking the willing satyrs with him. Meanwhile the Cyclops rushes to the mountain peak to try and sink the departing ship with boulders (ll. 661–707).

Euripides is not the only ancient dramatist who wrote a Cyclops satyr play. Aristias of the early fifth century did also. But Cyclops is apparently the only play by Euripides with a particular Homeric foundation. Euripides' play combines the myth of Dionysus's capture by pirates with the episode in Homer's Odyssey of Odysseus' encounter with the cyclops Polyphemus. In this scenario Euripides inserts Silenus and the satyrs, comic characters.

The satyr play as a medium was generally understood as a "tragedy at play". It relied extensively on the multifarious connotations which surrounded the concepts of "playfulness (paidia), education (paideia), child (pais), slave (pais), playful (paidikos), and childishness (paidia)". In Cyclops Euripides employed "metapoetically loaded terms" like second and double and new to highlight interactions with his sources, familiar and foundational texts in Athenian education. The characters in Cyclops are not ignorant of Euripides' sources. "Silenus 'knows his Odyssey rather well'". Euripides' Cyclops knows about the Trojan War and gives Odysseus his opinion of it. By playing with metapoetic images throughout the play Euripides fostered "a collective consciousness" in his democratic audience and facilitated their recognition that cooperation was necessary throughout Athens if they were to overcome their enemies.

Both the Homeric episode and Euripides' Cyclops are based on the blinding of the Cyclops. It was almost certainly known by Euripides' audience that a particular Alcander had stuck a stick into the eye of Lycurgus the Spartan lawgiver. On one level of Euripides' play Alcibiades thrusts a stake into the eye of "a gross caricature of a Spartan", expressing "a shift of political alliances ostensibly achieved by Alcibiades". Like Sophocles' Philoctetes, Euripides' Cyclops made an appeal on behalf of Alcibiades that he be allowed to return from exile. Euripides also encouraged his audience to consider the recent Athenian enterprise against Sicily, which was undertaken for greed against an intractable and difficult enemy when Athens could barely provide money or men and which did not go well.