Career
Cornelis never married. Cornelis de Graeff was a Canon of Saint Pieter at Utrecht. Most of the time he resided at his castle Ilpenstein.
He also owned Bronstee, a country estate near Heemstede.
The two famous paintings, both by Rembrandt, can be seen today at Wilhelmshöhe in Kassel. De Graeff also owned Frans Halsens painting Catharina Hooft with her Nurse.