William James Müller (1812-1845) was a British landscape and figure painter, the best-known artist of the Bristol School. Müller was born at Bristol, the son of J. S. Müller, a Prussian from Danzig, curator of a museum in Bristol.

He first studied painting under James Baker Pyne. His early pictures were mostly of the scenery of Gloucestershire and Wales, and he learned much from his study of Claude, Ruysdael, and earlier landscape-painters.

He witnessed the 1831 Bristol riots and recorded some of the scenes in a series of "raw and brilliant oil and watercolour sketches". In 1833, he exhibited at the Royal Academy for the first time, showing Destruction of Old London Bridge-Morning. The next year he made a tour through France, Switzerland, and Italy.

He died at Bristol on 8 September 1845. Following his death, his work was in great demand; leading to the production of a considerable number of fakes.