Worcester Reed Warner was an American mechanical engineer, entrepreneur, manager, astronomer, and philanthropist. With Ambrose Swasey he cofounded the Warner & Swasey Company.

The Warner & Swasey Company was an American manufacturer of machine tools, instruments, and special machinery. It operated as an independent business firm, based in Cleveland, from its founding in 1880 until its acquisition in 1980. It was founded as a partnership in 1880 by Worcester Reed Warner (1846–1929) and Ambrose Swasey (1846–1937). The company was best known for two general types of products: astronomical telescopes and turret lathes. It also did a large amount of instrument work, such as equipment for astronomical observatories and military instruments The themes that united these various lines of business were the crafts of toolmaking and instrument-making, which have often overlapped technologically. In the decades after World War II, it also entered the heavy equipment industry with its acquisition of the Gradall brand.