Christian I, known as "the Quarrelsome" (died 1167) was Count of Oldenburg from 1143 to 1167. He was son of Elimar II, Count of Oldenburg and his wife Eilika von Werl-Rietberg, daughter of Count Heinrich von Rietberg.
- Maurice, Count of Oldenburg (c1145 - c1211)
He is a direct male-line ancestor of Prince Philip, Duke of Edinburgh, and thus of Charles, Prince of Wales, the heir apparent to the British crown. He is also a direct male-line ancestor of the Danish queen and the Norwegian king.