Mimesis (; Ancient Greek: μίμησις, mīmēsis) is a term used in literary criticism and philosophy that carries a wide range of meanings, including imitatio, imitation, nonsensuous similarity, receptivity, representation, mimicry, the act of expression, the act of resembling, and the presentation of the self.

The original Ancient Greek term mīmēsis (μίμησις) derives from mīmeisthai (μιμεῖσθαι, 'to imitate'), itself coming from mimos (μῖμος, 'imitator, actor'). In ancient Greece, mīmēsis was an idea that governed the creation of works of art, in particular, with correspondence to the physical world understood as a model for beauty, truth, and the good. Plato contrasted mimesis, or imitation, with diegesis, or narrative. After Plato, the meaning of mimesis eventually shifted toward a specifically literary function in ancient Greek society.

One of the best-known modern studies of mimesis—understood in literature as a form of realism—is Erich Auerbach's Mimesis: The Representation of Reality in Western Literature, which opens with a comparison between the way the world is represented in Homer's Odyssey and the way it appears in the Bible.

In addition to Plato and Auerbach, mimesis has been theorised by thinkers as diverse as Aristotle, Philip Sidney, Samuel Taylor Coleridge, Adam Smith, Gabriel Tarde, Sigmund Freud, Walter Benjamin, Theodor Adorno, Paul Ricœur, Luce Irigaray, Jacques Derrida, René Girard, Nikolas Kompridis, Philippe Lacoue-Labarthe, Michael Taussig, Merlin Donald, Homi Bhabha, Roberto Calasso, and Nidesh Lawtoo. During the nineteenth century, the racial politics of imitation towards African Americans influenced the term mimesis and its evolution.