Ranulf I of Poitiers was a Count of Poitiers and Duke of Aquitaine.
He is considered a possible son of Gerard, Count of Auvergne and Hildegard / Matilda, daughter of Louis the Pious and Ermengarde.
Although not much is known about Ranulf I, he died in 866 in Aquitaine, France.
His son, Ranulf II of Poitiers, then inherited Poitiers and later acquired Aquitaine. Through the duchy of Aquitaine, he is the ancestor of Eleanor of Aquitaine, thus he is also an ancestor of the present-day British Royal Family.