In Greek mythology, Pyramus and Thisbe (Ancient Greek: Πύραμος καὶ Θίσβη, romanized: Púramos kaì Thísbē) are a pair of ill-fated lovers from Babylon, whose story is best known from Ovid's narrative poem Metamorphoses. The tragic myth has been retold by many authors.

Pyramus and Thisbe's parents, driven by rivalry, forbade their union, but they communicated through a crack in the wall between their houses. They planned to meet under a mulberry tree, but a series of tragic misunderstandings led to their deaths: Thisbe fled from a lioness, leaving her cloak behind, which Pyramus found and mistook as evidence of her death. Believing Thisbe was killed by the lioness, Pyramus died by suicide, staining the mulberry fruits with his blood. Thisbe, upon finding Pyramus dead, also killed herself. The gods changed the color of the mulberry fruits to honor their forbidden love.

Ovid's version is the oldest surviving account, but the story is likely to have originated from earlier myths in Cilicia. The tale has been adapted in various forms, inspiring works such as Shakespeare's Romeo and Juliet and A Midsummer Night's Dream, as well as modern adaptations in literature, opera, and popular culture. The story is depicted in works of art from ancient Roman mosaics to Renaissance paintings.

Pyramus and Thisbe are two lovers in the city of Babylon who occupy connected houses. Their respective parents, driven by rivalry, forbid them to wed. Through a crack in one of the walls they whisper their love for each other. They arrange to meet near a tomb under a mulberry tree and state their feelings for each other. Thisbe arrives first, but upon seeing a lioness with a bloody mouth from a recent kill, she flees, leaving behind her cloak. When Pyramus arrives, he is horrified at the sight of Thisbe's cloak: the lioness had torn it and left traces of blood behind, as well as its tracks. Assuming that a wild beast had killed her, Pyramus kills himself, falling on his sword, a typical Babylonian way to commit suicide, and in turn splashing blood on the white mulberry leaves. Pyramus' blood stains the white mulberry fruits, turning them dark. Thisbe returns, eager to tell Pyramus what had happened to her, but she finds Pyramus' dead body under the shade of the mulberry tree. Thisbe, after praying to their parents and the gods to have them buried together and a brief period of mourning, stabs herself with the same sword. In the end, the gods listen to Thisbe's lament, and forever change the color of the mulberry fruits into the stained color to honor forbidden love. Her wish to be buried together with Pyramus is also granted; the lovers' ashes are preserved in one urn. Pyramus and Thisbe are models of love that is faithful to the very end.

Ovid's is the oldest surviving version of the story, published in 8 AD, but he adapted an existing aetiological myth. While in Ovid's telling Pyramus and Thisbe lived in Babylon, and Ctesias had placed the tomb of his imagined king Ninus near that city, the myth probably originated in Cilicia (part of Ninus' Babylonian empire) as Pyramos is the historical Greek name of the local Ceyhan River. The metamorphosis in the primary story involves Pyramus changing into this river and Thisbe into a nearby spring. A 2nd-century mosaic unearthed near Nea Paphos on Cyprus depicts this older version of the myth. This alternative version also survives in the progymnasmata, a work by Nicolaus Sophista, a Greek sophist and rhetor who lived during the fifth century AD.

Ovid's rendition of the tale seems to have been inspired by an earlier genre of Greek tragic love stories in which a woman is killed accidentally or indirectly by a man, and following that he dies or commits suicide in grief; such examples include Anthippe and Cichyrus and Cyanippus and Leucone.

The story of Pyramus and Thisbe appears in Giovanni Boccaccio's On Famous Women as biography number twelve (sometimes thirteen) and in his Decameron, in the fifth story on the seventh day, where a desperate housewife falls in love with her neighbor, and communicates with him through a crack in the wall, attracting his attention by dropping pieces of stone and straw through the crack.

In the 1380s, Geoffrey Chaucer, in his The Legend of Good Women, and John Gower, in his Confessio Amantis, were the first to tell the story in English. Gower altered the story somewhat into a cautionary tale. John Metham's Amoryus and Cleopes (1449) is another early English adaptation.