Sir William Ramsay KCB FRSE FRS (1852–1916) 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" (along with Lord Rayleigh who received the Nobel Prize in Physics that same year for the discovery of argon).

Ramsay was born in Glasgow on 2 October 1852, the son of civil engineer William Ramsay and Catherine, née Robertson. He was a nephew of the geologist Sir Andrew Ramsay.

He attended the Glasgow Academy and then continued his education at the University of Glasgow under Thomas Anderson and then went to study in Germany at the University of Tübingen with Wilhelm Rudolph Fittig where his doctoral thesis was entitled Investigations in the Toluic and Nitrotoluic Acids.

Ramsay returned to Glasgow as Anderson's assistant at the Anderson College. He was appointed Professor of Chemistry at the University College of Bristol in 1879 and married Margaret Buchanan in 1881. In the same year he became the Principal of University College, Bristol, and somehow managed to combine that with active research both in organic chemistry and on gases.