MonthyonMonthyon is a commune in the Seine-et-Marne department of the Île-de-France region in north-central France.WWW Official SiteNotable residentsThe Belgian painter Eugène Boch lived in the Villa La Grimpette. In 1959, French actor Jean-Claude Brialy acquired a château in the commune; he lived there, with his partner, until he died in 2007.DemographicsFrom a population of 858 in 1975, Monthyon grew to 1,730 by 2018. The inhabitants of Monthyon are called Monthyonnais.