Some years ago I met Franz Denz from Mönchengladbach who told me that the name "Denz" had been traced back to a heretic named Gaudenzio. Apparently the name was shortened to Denz when migration to Germany took place round about 390AD.
Is there anyone out there with more information please?

My father was Jack Adolf Denz, born in UK and his father was Gustav Denz born in Germany.