William Mason was a master mechanical engineer and builder of textile machinery and railroad steam locomotives. He founded Mason Machine Works of Taunton, Massachusetts. His company was a significant supplier of locomotives and rifles for the Union Army during the American Civil War. The company also later produced printing presses.

The Mason Machine Works was a machinery manufacturing company located in Taunton, Massachusetts, between 1845 and 1944. The company became famous for an early invention by its creator, William Mason, the self-acting mule, first patented in 1840. The company also later produced locomotives, rifles during the American Civil War, and later printing presses. However, the production of textile machinery would remain the company's core business during the late 19th century, until its decline in the 1920s.