The Monobloc chair is a lightweight stackable polypropylene chair, usually white in colour, often described as the world’s most common plastic chair. The name comes from mono- (“one”) and bloc (“block”), meaning an object forged in a single piece.

The Monobloc chair is so named because it is injection moulded from thermoplastic as one piece rather than being assembled from multiple pieces. Many variations and styles exist but all are designed to allow the chair to be made quickly and cheaply through injection molding. A common material used is thermoplastic polypropylene.

Numerous variants exist. Their light weight and stackable design eases both their deployment and storage.