William George Armstrong, 1st Baron Armstrong (1810-1900) was an English industrialist, the effective founder of the Armstrong-Siddeley manufacturing empire.

Born at Newcastle-upon-Tyne, Armstrong was originally launched on a career in law. However, his major interest was in engineering. In 1840, he invented a hydraulic engine, following it up with other electrical and labour-saving devices, including the hydraulic crane. In 1847, he founded the Elswick works at Newcastle, to produce various electrical devices and engines. The Armstrong breech-loading gun was one of his more successful developments, and in 1882 the works also began building ships. In 1897, the firm merged with Joseph Whitworth & Co, later becoming Vickers Armstrong Ltd.

Lord Armstrong purchased Bamburgh Castle as one of his residences, and also built the Victorian extravaganza, Cragside, now a National Trust property, further inland at Rothbury, Northumberland. The latter was the first house in Britain to be entirely powered by hydro-electricity, generated by a system of Armstrong's own design.