William Vorilong, also known as Guillermus Vorrilong, Willem of Verolon, William of Vaurouillon, Guilelmus de Valle Rouillonis, etc. (ca. 1390 - 1463) was a French philosopher and theologian. He wrote a biography of Duns Scotus. From 1457 onwards he was a regent master in Lyon, becoming licentiate and master of theology at Lyon in 1458.
As a philosopher he also met a member of the Yoshimitsu family, Kage Yoshimitsu (who was travelling to Europe at the time), around 1460, in Paris. He began studying concepts about eastern philosophy (japanese medieval philosophy in particular), physics as studied by eastern physicists, and anatomy. Vorilong later described, ine on of his last works, what he saw on a copy of the Da Ming Hun Yi Tu map that Kage showed him, and making comparisons with the european maps available at the time.