Paul Hermann Müller (January 12, 1899 - October 12, 1965) was a Swiss chemist and winner of the 1948 Nobel Prize in Physiology or Medicine for his 1939 discovery of the insecticidal properties of DDT.

Müller was born in Olten/Solothurn. After receiving his doctorate in 1925 he worked for J.R. Geigy AG in Basel. Here he made his famous discovery in the autumn of 1939.

Müller's Nobel Prize was given "for his discovery of the high efficiency of DDT as a contact poison against several arthropods." This was the first time that the prize in medicine had been given to someone who was not a doctor.

Müller died in Basel in 1965.