William M. Henderson (1831-1904) was a mechanical engineer and inventor who spent most of his career in Philadelphia. Henderson was born April 16, 1831 in Edinburgh, Scotland to Thomas Henderson (1800-1847) and Jessie Murray (1803-1870).

His first recorded employment was as a mechanical engineer for the London & North Western Railway in 1847. By 1857, he had emigrated to America and was working at the Union Works of Baltimore. Here he patented a slide valve and a force pump. There followed a few years builing railroad bridges and similar works in Chile, but by 1865 he had settled in Philadelphia and formed the partnership Brinton & Henderson, pump manufacturers, doing business as the Philadelphia Hydraulic Works. This firm was succeeded by William M. Henderson & Co.

Henderson invented a hydraulic brake for railroads around 1873 and formed a separate company to manufacture it, although it quickly lost out to the Westinghouse air brake. By the late 1870s, Henderson's interest had turned to steel-making, partuclarly in the blowing engines used in the Bessemer process and the engines and other machinery of rolling-mills.

In 1857, Henderson married Rebecca Tagart (1837-1897) in Baltimore, Maryland. They had Jessie Murray (1859-1915), William Claude (1861-1903), Virginia (1867-1952), and Helen Weston (1871-1956). Henderson died May 5, 1904 in Pennsylvania and is buried in Bala Cynwyd, Pennsylvania.