William Murdoch (sometimes spelled Murdock) (21 August 1754 – 15 November 1839) was a Scottish chemist, inventor, and mechanical engineer.
Murdoch was employed by the firm of Boulton & Watt and worked for them in Cornwall, as a steam engine erector for ten years, spending most of the rest of his life in Birmingham, England.
Murdoch was the inventor of the oscillating cylinder steam engine, and gas lighting is attributed to him in the early 1790s, as well as the term "gasometer". However the Dutch-Belgian Academic Jean-Pierre Minckelers had already published on coal gasification and gas lighting in 1784, and had used gas to light his auditorium at the University of Leuven from 1785. Archibald Cochrane, 9th Earl of Dundonald, had also used gas for lighting his family estate from 1789 onwards.
Murdoch also made innovations to the steam engine, including the sun and planet gear and D slide valve. He invented the steam gun and the pneumatic tube message system, and worked on one of the first British paddle steamers to cross the English Channel. Murdoch built a prototype steam locomotive in 1784, and made a number of discoveries in chemistry.