King Charles VI of
France's wife was Isabeau de Bavière (Isabeau of Bavaria) (1371-24 Sep 1435). She was also known as
Isabelle. See
http://en.wikipedia.org/wiki/Charles_VI_of_France and
http://en.wikipedia.org/wiki/Image:France-3rdValois.png (lists her as
Isabelle).
I believe Isabeau's an Old French form of
Isabel, but I'm not 100% percent certain (OK, I'm around 80% certain ;-)).
Miranda