Tags: Noble.
John I Count of Oldenburg (c. 1204 – c. 1270) was a ruling Count of Oldenburg from 1233 until his death.His father Christian II had ruled jointly with his uncle Otto I. After Christian II died in 1233 Otto I acted as guardian for the underage John I. When John I came of age he ruled jointly with Otto I. After Otto I died in 1251 John I ruled alone.In 1244 Otto I and John I together founded the Cistercian Rosenthal monastery in Menslage.