Katharina von Kleve

It appears that nothing is known about her, and even the Kleve genealogy doesn't list her. She might have been an invention of the Visconti family, which desperately needed some ancestors of highest nobility to gain noble status as well. Or "Kleve" could mean "Chiavenna" (German: Cläven or Kleven) instead, which would make more sense. Geographically closer, similar social context.