Paul Muller (1910–2000) was a French astronomer born in Lorquin (Moselle), affiliated with the Paris Observatory (Meudon section). A specialist in visual double stars, he invented the double-image micrometer in 1937, which significantly advanced the precision of angular separation measurements, and discovered more than 700 binary systems over his career. He twice served as president of IAU Commission 26 (double stars): 1952–1958 and 1976–1979. A collaborator of André Danjon at the Paris Observatory, he contributed to satellite observation programmes during the International Geophysical Year.