The Frogs (Ancient Greek: Βάτραχοι, romanized: Bátrakhoi; Latin: Ranae, often abbreviated Ran. or Ra.) is a comedy written by the Ancient Greek playwright Aristophanes. It was performed at the Lenaia, one of the Festivals of Dionysus in Athens, in 405 BC and received first place.

The play features the comical katabasis of the god of theater Dionysus, with his slave Xanthias, in order to revive the late tragedian Euripides. Dionysus is frustrated with tragedy's decline in quality after the playwright's recent passing, and concerned about theatre's future as the city of Athens struggles in the Peloponnesian War. During the pair's journey through the underworld, the god cravenly and unsuccessfully attempts to evade trouble after masquerading as Heracles, still infamous for his prior kidnapping of the guard-dog Cerberus. At the palace of Pluto, Dionysus then adjudicates a fierce debate between Euripides and Aeschylus for the underworld's throne of tragic drama. Aeschylus wins due to his pragmatism, and Dionysus ends up reviving him instead. The play's title derives from the first choral interlude (parodos), where the chorus, a group of frogs, exasperate Dionysus in song.

A defining work of Old Comedy, The Frogs contains a mix of irreverent humour and highbrow satire of Athenian politics, religion and theatre, commenting on poetry's moral role in civic and political life. The play is notably characterised by its extensive literary criticism and references: the second half's agon between Euripides and Aeschylus examines both figures' differing approaches to tragedy. In 1974, the play was loosely adapted into a musical of the same name by Stephen Sondheim and Burt Shevelove. This adaptation features the Irish playwright George Bernard Shaw and English playwright William Shakespeare, in place of Euripides and Aeschylus respectively.

Dionysus is travelling with his slave Xanthias to the underworld. Xanthias, carrying Dionysus' baggage, attempts to make fun of his heavy load with toilet humour – the jokes he believes the audiences are expecting from this situation – but the god frustratedly pre-empts his remarks. To find a reliable path to Hades, Dionysus seeks advice from his half-brother Heracles, who had been there before in order to retrieve the hell hound Cerberus. Dionysus shows up at his doorstep dressed in a lion-hide and carrying a club. Heracles, upon seeing the effeminate Dionysus dressed up like himself, cannot help laughing. Dionysus explains his motivation for travelling to Hades: to bring the playwright Euripides back from the dead, in order to correct what he sees as the sorry state of Athens' tragedians. When Dionysus asks which road is the quickest to get to Hades, Heracles tells him that he can hang himself, drink poison or jump off a tower. Dionysus opts for the longer journey, which Heracles himself had taken, across a lake (possibly Lake Acheron).

When Dionysus arrives at the lake, Charon ferries him across. Xanthias, being a slave, is not allowed in the boat, and has to walk around it, while Dionysus is made to help row the boat. The eponymous chorus of frogs (the only instance of frogs in the play) sing the parodos, the first choral interlude. Their croaking refrain – Brekekekèx-koàx-koáx (Greek: Βρεκεκεκὲξ κοὰξ κοάξ) – greatly annoys Dionysus, who engages in a mocking debate (agon) with the frogs. When he arrives at the shore, Dionysus meets up with Xanthias, who teases him by claiming to see the frightening monster Empusa. A second chorus composed of spirits of Dionysian Mystics soon appear.

The next encounter is with Hades' janitor, who mistakes Dionysus for Heracles due to his attire. Still angry over Heracles' theft of Cerberus, he threatens to unleash several monsters on him in revenge. Frightened, Dionysus trades clothes with Xanthias. A maid then arrives and is happy to see Heracles. She invites him to a feast with virgin dancing girls, and Xanthias is more than happy to oblige, but Dionysus quickly wants to trade back the clothes. Dionysus, back in the Heracles lion-skin, encounters more people angry at Heracles, and so he makes Xanthias trade a third time. When the janitor returns to confront the alleged Heracles, Xanthias offers him his "slave" (Dionysus) for torturing, to obtain the truth as to whether or not he is really a thief. The terrified Dionysus tells the truth that he is a god. After each is whipped, the janitor admits he is unable to tell which one is a god, and takes Dionysus to be verified offstage by Pluto and Persephone. In the parabasis, the chorus comments on the political state of Athens, criticising its inconsistency with granting citizenships, and its lack of meritocracy.

Working in Pluto's palace, Xanthias and another slave delight in mocking their own masters: the latter explains the ongoing contest between Euripides and Aeschylus. Euripides, who had only just recently died, is challenging the great Aeschylus for the seat of "Best Tragic Poet" at the dinner table of Pluto, the ruler of the underworld. (It is explained that Sophocles has forgone participation in the contest, due to his deferentiality towards Aeschylus.) A contest is held with Dionysus as judge. The two playwrights take turns quoting verses from their plays and making fun of the other. Euripides argues the characters in his plays are better because they are more true to life and logical, whereas Aeschylus believes his idealized characters are better as they are heroic and models for virtue. Aeschylus mocks Euripides' verse as predictable and formulaic by having Euripides quote lines from many of his prologues, each time interrupting the declamation with the same phrase "ληκύθιον ἀπώλεσεν" ("... lost his little flask of oil"). (The passage has given rise to the term lekythion for this type of rhythmic group in poetry.) Euripides counters by demonstrating the alleged monotony of Aeschylus' choral songs, parodying excerpts from his works and having each citation end in the same refrain ἰὴ κόπον οὐ πελάθεις ἐπ᾽ ἀρωγάν; ("oh, what a stroke, won't you come to the rescue?", from Aeschylus' lost play Myrmidons). Aeschylus retorts by mocking Euripides' choral meters and lyric monodies with castanets.

In a first attempt to end the debate, a balance is brought in and each are told to tell a few lines into it. Whoever's lines have the most "weight" will cause the balance to tip in their favour. Euripides produces verses of his that mention, in turn, the ship Argo, Persuasion and a mace. Aeschylus responds with the river Spercheios, Death and two crashed chariots, each with a dead charioteer. Since the latter verses refer to "heavier" objects, Aeschylus wins, but Dionysus is still unable to decide whom he will revive, so he reveals the intent of his visit: to save the city of Athens, currently at the losing end of the Peloponnesian War, and its dramatic scene by extension. He decides to take the poet who gives the best political advice: firstly, what the Athenians should do with the exiled Alcibiades, and secondly, how each of the poets thinks the city can be saved. Euripides gives cleverly worded but essentially meaningless answers while Aeschylus provides more practical advice, and Dionysus decides to take Aeschylus back instead of Euripides. Pluto allows Aeschylus to return to life so that Athens may be succoured in her hour of need and invites everyone to a round of farewell drinks. Before leaving, Aeschylus proclaims that Sophocles should have his chair while he is gone, not Euripides.