Geoffrey I, Duke of Brittany
| Geoffrey I | |
|---|---|
| Duke of Brittany | |
| Born | c. 980 Rennes, County of Rennes, Duchy of Brittany |
| Died | 20 November 1008 Nantes, Loire-Atlantique, Pays de la Loire, France |
| Burial | Brittany |
| Spouse | Hawise |
| Issue | Alan III, Duke of Brittany Odo, Count of Penthièvre |
| House | House of Rennes |
| Father | Conan I, Duke of Brittany |
| Mother | Ermengarde-Gerberga of Anjou |
Geoffrey I (c. 980 – 20 November 1008), also known as Geoffrey of Rennes and Geoffrey Berengar, was Duke of Brittany from 992 until his death, and also Count of Rennes (ruler of the Romano-Frankish civitas of Rennes) by right of succession. The eldest son of Duke Conan I of Brittany, he assumed the title of Duke of Brittany upon his father's death in 992. Brittany had long been an independent state, but he had little control over much of Lower Brittany.