The Count of Rennes was originally the ruler of the Romano-Frankish civitas of Rennes. From the middle of the ninth century these counts were Bretons with close ties to the Duchy of Brittany, which they often vied to rule. From 990 the Counts of Rennes were usually Dukes of Brittany. In 1203 the county was integrated into the ducal demesne.
???–876 Gurwant, also Duke from 874876–888 Judicael888–903 unknown903–953 Judicael Berengar958–992 Conan I the Crooked, also Duke from 990992–1008 Geoffrey I, also Duke1008–1040 Alan I, also Duke; granted the Countship of Penthievre to his brother Eudes, thereby founding the Cadet Branch of the House of Rennes1040–1066 Conan II, also Duke1066–1082 Geoffrey II Grenonat1066–1072 Hawise (in opposition to Geoffrey II), also Duchess1082–1084 Hoel I (in opposition to Geoffrey II from 1066), also Duke from 10661084–1112 Alan II Fergant, also Duke1112–1148 Conan III the Fat, also Duke1148–1156 Hoel II1156–1166 Conan IV the Young, also Duke until 11661166–1181 Henry Curtmantle, as guardian of Constance1181–1186 Geoffrey III, Count of Rennes and Duke of Brittany jure uxoris1166–1201 Constance, also Duchess from 11661196–1203 Arthur, also DukeThe County of Rennes was merged permanently into the Ducal crown of Brittany, and subsequently the crown of France, through Constance's descendants
