Dietrich I of the Mark
Dietrich I of the Mark (1336–1406) was the third son of Count Adolf II of the Mark and Margaret of Cleves. He became provost of Cologne Cathedral, but after being elected Bishop of Liège he declined the see and returned to secular life.
When his brother Adolf secured Cleves in 1368, Dietrich received most of the Cleves lands on the right bank of the Rhine, ruling there as lord until his death.