Jacques Guy is a French linguist, born 2 October 1944 and who has lived in Australia since 1968. He studied at the École des Langues Orientales (School of Oriental Languages, renamed since to the Institut national des langues et civilisations orientales) in Paris, France.
In 1991 he proposed the 'Frogguy' transcription alphabet for the Voynich Manuscript. He is also interested in Rongorongo (Wikipedia page [1]; the article on its decipherment is at [2]; there is more information on the Spanish Wikipedia page [3]).
A longer biography can be found on Wikipedia at [4] and some of his VM programs can be found here [5].