Eugen Dieth (18 November 1893, in Neukirch an der Thur – 24 May 1956, in Zollikon) was a Swiss linguist, phonetician and dialectologist.

Between 1927 and 1936 he worked as a part-time editor for the Schweizerisches Idiotikon and between 1934 and his unexpected death from a stroke in 1956 he was the director of the Phonogram Archives of the University of Zurich.

It postulates that the vernacular spelling ought to reflect the phonological characteristics and individuality of the various Swiss dialects.

In its less strict form, it tries to limit itself to the usage of the letters and diacritics that are available on a simple typing machine.

More importantly, however, he initiated the work for the Survey of English Dialects and compiled—together with Harold Orton—the Questionnaire for a Linguistic Atlas of England.