Dionis de Lys or Lis was a Flemish conquistador in the service of the Spanish monarchy. He attended the first foundation of Buenos Aires by Pedro de Mendoza.
Dionis was born in Lys, County of Flanders, the son of Johannes de Lys and Barboxa de Leys. He had arrived to the RÃÂo de la Plata in the expedition of Pedro de Mendoza, together with a contingents of Flemish adventurers.
Lys traveled to Asunción, where he formed a family, a daughter Catalina de Lys was married to Luis Alegre, also born in Flanders.