Henry Cavendish FRS (10 October 1731 – 24 February 1810) was a British scientist noted for his discovery of hydrogen or what he calls "inflammable air".

He describes the density of inflammable air, which forms water on combustion, in a 1766 paper "On Factitious Airs".

Antoine Lavoisier later reproduces Cavendish's experiment and gives the element its name.

Cavendish is also known for the Cavendish experiment, his measurement of the Earth's density, and early research into electricity.