Geoffrey I (Gauzfred I) (d. after 985), possibly the son of Geoffroy, Viscount of Chartres, is the first Viscount of Châteaudun[1] and thus regarded as the founder of the House of Châteaudun, vassal of the House of Blois.
It is assumed that Geoffrey descended from Rorgon I, Count of Maine, and therefore part of the Rogonid/Rorgonid dynasty.
[2] Little is known about Geoffrey, other than he was closely associated with Hardouin, Archbishop of Tours.
In Christian Settipani and Katharine S. B. Keats-Rohan, Onomastique et Parenté dans l'Occident médiéval.
Tout, Thomas Frederick, The Empire and the Papacy: 918-1273, Periods of European History, London: Rivingtons, 1928