Ekphrasis or ecphrasis (from the Greek) is a rhetorical device indicating the written description of a work of art. It is a vivid, often dramatic, verbal description of a visual work of art, either real or imagined. Thus, "an ekphrastic poem is a vivid description of a scene or, more commonly, a work of art." In ancient times, it might refer more broadly to a description of any thing, person, or experience. The word comes from the Greek ἐκ ek and φράσις phrásis, 'out' and 'speak' respectively, and the verb ἐκφράζειν ekphrázein, 'to proclaim or call an inanimate object by name'.

The works of art described or evoked may be real or imagined; and this may be difficult to discern. Ancient ekphrastic writing can be useful evidence for art historians, especially for paintings, as virtually no original Greco-Roman examples survive.

An early example of ekphrasis comes in Plato's Phaedrus, where Socrates is discussing writing and painting with Phaedrus, in a lovely spot by a plane tree outside the city. His speech, praising the tree and its location goes in great detail — describing the tree's size, the shade it gives, the blossoms, a nearby spring, etc., and is indeed considered over the top by Phaedrus. Later, he says, "You know, Phaedrus, that is the strange thing about writing, which makes it truly correspond to painting. The painter's products stand before us as though they were alive, but if you question them, they maintain a most majestic silence. It is the same with written words; they seem to talk to you as if they were intelligent, but if you ask them anything about what they say, from a desire to be instructed, they go on telling you just the same thing forever".

The fullest example of ekphrasis in antiquity can be found in Philostratus of Lemnos' Eikones which describes 64 pictures in a Neapolitan villa. Modern critics have debated as to whether the paintings described should be considered as real or imagined, or the reader left uncertain. Ekphrasis is described in Aphthonius' Progymnasmata, his textbook of style, and later classical literary and rhetorical textbooks, and with other classical literary techniques. It was keenly revived in the Renaissance.

In the Middle Ages, ekphrasis was less often practiced, especially regarding real objects. Historians of medieval art have complained that the accounts of monastic chronicles recording now vanished art concentrate on objects made from valuable materials or with the status of relics. They rarely give more than the cost and weight of objects, and perhaps a mention of the subject matter of the iconography.

The Renaissance and Baroque periods made much use of ekphrasis, typically mainly of imagined works. In Renaissance Italy, Canto 33 of Ariosto's Orlando Furioso describes a picture gallery created by Merlin. In Spain, the playwright Lope de Vega often used allusions and descriptions of Italian art in his works, and included the painter Titian as one of his characters. Calderón de la Barca also incorporated works of art in dramas such as The Painter of his Dishonor. Miguel de Cervantes, who spent his youth in Italy, used many Renaissance frescoes and paintings in Don Quixote and many of his other works. In England, Shakespeare briefly describes a group of erotic paintings in Cymbeline, but his most extended exercise is a 200-line description of the Greek army before Troy in The Rape of Lucrece. Ekphrasis seems to have been less common in France during these periods.

Herman Melville's Moby Dick (1851), according to Christopher Phillips, introduces ekphrasis as "a new turn in American epic literature", and Phillips singles out the painting in the Spouter-Inn.

Peter Bly has described the many uses of art in the works of Benito Pérez Galdós. For example, in La incógnita (1889), there are many allusions and descriptions of Italian art, including references to Botticelli, Mantegna, Masaccio, Raphael, Titian, and others. In Our Friend Manso (1882), the narrator describes two paintings by Théodore Géricault to point to the shipwreck of ideals. In this novel, as well as in Miau (1888), as Frederick A. de Armas has pointed out, there are numerous allusive ekphrasis to paintings of Bartholomew the Apostle.