Petrus Peregrinus de Maricourt (Latin), Pierre Pelerin de Maricourt (French), or Peter Peregrinus of Maricourt (fl. 1269), was a French mathematician, physicist, and writer who conducted experiments on magnetism and wrote the first extant treatise describing the properties of magnets. His work is particularly noted for containing the earliest detailed discussion of freely pivoting compass needles, a fundamental component of the dry compass soon to appear in medieval navigation. He also wrote a treatise on the construction and use of a universal astrolabe.