John H. Beynon FRS[1][2] (29 December 1923 – 24 August 2015) was a Welsh chemist and physicist known for his work in mass spectrometry.

He did not attend graduate school, instead deciding to join the Fighting Vehicles Research Establishment where he served between 1943 and 1947 developing tank fire-control systems.

[10] Between 1947 and 1950, Beynon constructed what was to become the first mass spectrometer designed to study organic compounds unrelated to petroleum.

Beynon took a position as Professor of Chemistry and Director of the Mass Spectrometry Center at Purdue University in 1968.

[18][19] In 1987, Beynon was founding editor-in-chief of the journal Rapid Communications in Mass Spectrometry.