William Ramsay (October 2, 1852–July 23, 1916) was a British chemist.

Ramsay was born in Glasgow, the son of William Ramsay, C.E. and Catherine, née Robertson. He was a nephew of the geologist Sir Andrew Ramsay.

It was in inorganic chemistry that his most celebrated discoveries were made. As early as 1885–1890 he published several notable papers on the oxides of nitrogen and followed these up with the discovery of argon, helium, neon, krypton, and xenon.

Sir William Ramsay received the Nobel Prize for chemistry in 1904.

He died at High Wycombe, Buckinghamshire, on July 23 1916.