Alan III od Rennesa (997 – 1. oktobar 1040) ili Alan III od Bretanje (francuski: Alain III de Bretagne) bio je vojvoda Bretanje od 1008. do smrti. Bio je sin vojvode Geoffreya I i Hawise od Normandije. U trenutku očeve smrti bio je malodoban, te mu je majka bila regent.[1] Alan se oženio za Berthu, kćer grofa Oda II od Bloisa s kojom je imao namanje dvoje djece - svog nasljednika Conana II i kćer Hawise od Bretanje koja se udala za Hoel od Cornouaillea.
Godine 1032. je svojoj sestri Adele, koja se zaredila, sagradio samostan Saint George.
Waroch • Judicael ap Hoel • Morman • Wihomarc •Nominoe•Erispoe• Salomon • Pasquitan • Gurvand • Judicael • Alan I • Gourmaelon
Kuća Nantes
938–958
Alan II (938–952) • Drogo (952–958) • Hoel I (960–981) • Guerech (981-988) • Alan (III) (988-990)
Kuća Rennes
958–1072
Conan I (958–992) • Geoffrey I (992–1008) •Alan III (1008–1040) • Odo I (1008–1034) • Conan II (1040–1066) • Hawise (1066–1072) • with Hoel II (1066–1072)
Kuća Cornouaille
1072–1156
Alan IV (1072–1112) • Conan III (1112–1148) • Bertha (1148–1156) • with Odo II (1148–1156)
Kuća Penthièvre
1156–1194
Conan IV (1156–1171) • Constance (1171–1194) • with Geoffrey II (1181–1186), • later Ranulph (1188–1194)
Kuća Plantagenet
1194–1203
Arthur I (1194–1203)
Kuća Thouars
1203–1221
Alix (1203-1221) • with Petar I (1213-1221)
Kuća Dreux
1221–1364
Jean I (1221-1286) • Jean II (1286–1305) • Arthur II (1305–1312) • John III (1312–1341) • Jeanne (1341–1364) • with Charles I (1341–1364)
Kuća Montfort
1341/65–1514
Jean IV (1341-1345) • Jean V (1345/65-1399) • John VI (1399–1442) • François I (1442–1450) • Pierre II (1450–1457) • Arthur III (1457–1458) • François II (1458–1488) •Anne (1488–1514) • with Charles II (1491–1498), • later Louis I (1499–1514)
