Yvain, the Knight of the Lion is an Arthurian romance by French poet Chrétien de Troyes. It was written c. 1180 simultaneously with Lancelot, the Knight of the Cart, and includes several references to the narrative of that poem. It is a story of knight-errantry, in which the protagonist Yvain is first rejected by his lady for breaking a very important promise, and subsequently performs a number of heroic deeds in order to regain her favour. The poem has been adapted into several other medieval works, including Iwein and Owain, or the Lady of the Fountain.

As a literary genre, the chivalric romance is a type of prose and verse narrative that was popular in the noble courts of high medieval and early modern Europe. They were fantastic stories about marvel-filled adventures, often of a chivalric knight-errant portrayed as having heroic qualities, who goes on a quest. It developed further from the epics as time went on; in particular, "the emphasis on love and courtly manners distinguishes it from the chanson de geste and other kinds of epic, in which masculine military heroism predominates."