Philipp Heinrich Emil Rupp (1 July 1898 – 10 April 1979) was a German physicist, regarded by many as a respectable and important experimentalist in the late 1920s.

In 1926 Rupp's canal ray experiments seemed to corroborate Albert Einstein's theories on wave–particle duality.

Although the validity of Rupp's experimental results had been challenged by other workers in the field repeatedly throughout his career, it was not until 1935 that his misdeeds were fully exposed.

Some fellow physicists at the AEG labs grew suspicious of Rupp when he claimed having accelerated protons at 500 kV, something he could not have the technical facilities to achieve.

He attached a psychiatric diagnosis by Dr. Emil von Gebsattel [de] that said he had written them under the influence of "dreamlike states" caused by psychasthenia.