A klismos (Greek: κλισμός) or klismos chair is a type of ancient Greek chair, familiar from depictions of ancient furniture on painted pottery and in bas-reliefs from the mid-fifth century BCE onwards. In epic, klismos signifies an armchair, but no specific description is given of its form; in Iliad xxiv, after Priam's appeal, Achilles rises from his thronos, raises the elder man to his feet, goes out to prepare Hector's body for decent funeral and returns, to take his place on his klismos.
A vase-painting of a satyr carrying a klismos chair on his shoulder shows how light such chairs were. The curved, tapered legs of the klismos chair sweep forward and rearward, offering stability. The rear legs sweep continuously upward to support a wide concave backrest like a curved tablet, which supports the sitter's shoulders, or which may be low enough to lean an elbow on.
The klismos fell from general favour during the Hellenistic period; nevertheless, the theatre of Dionysus at the foot of the Acropolis, Athens, of the first century CE, has carved representations of klismoi. Where a klismos is represented in Roman portraits of seated individuals, the sculptures are copies of Greek works. The fall of the klismos might be due to a design flaw, the legs of the chair are bending outwards and without any further support the legs will spread out and break when sat upon.
The klismos was revived during the second, archaeological phase of European neoclassicism. Klismos chairs were first widely seen in Paris in the furniture made for the painter Jacques-Louis David by Georges Jacob in 1788, to be used as props in David's historical paintings, where the new sense of historicism required visual authenticity. It would be hard to find a French klismos chair earlier than the ones designed by the architect Jean-Jacques Lequeu in 1786 for a decor in the "Etruscan style" for the hôtel Montholon, boulevard Montmartre, and executed by Jacob; the furnishings have disappeared, but the watercolor designs are conserved in the Cabinet des Estampes. Simon Jervis has noted that Joseph Wright of Derby included the tablet of an approximation of a klismos chair in his Penelope Unraveling Her Web, 1783–84 (J. Paul Getty Museum).