Sir William Ramsay, KCB FRSE (2 October 1852–23 July 1916) was a Scottish chemist who discovered the noble gases and received the Nobel Prize in Chemistry in 1904 "in recognition of his services in the discovery of the inert gaseous elements in air."

In 1887 he succeeded Alexander Williamson to the chair of Chemistry at University College London (UCL).
As early as 1885–1890 he published several notable papers on the oxides of nitrogen developing the skills that he would need for his subsequent work.
In the years that followed he discovered neon, krypton, and xenon.
In 1904 Ramsay received the Nobel Prize in Chemistry.
In 1910 he also made and characterized radon.
He died at High Wycombe, Buckinghamshire, on 23 July 1916 from nasal cancer at the age of 63 and was buried at Hazelmere Parish church.