Hawise of Rennes (Breton : Hawiz Breizh; French : Havoise de Bretagne) (c. 1024-1037 – 19 August 1072) was sovereign Duchess of Brittany from 1066 until her death.
She was the second child and heiress of Alan III, Duke of Brittany, by his wife, Bertha of Blois, and as such, a member of the House of Rennes. Hawise succeeded her older brother, Conan II, who was assassinated by poisoning on 11 December 1066. 
Little is known of the life of Hawise of Rennes. She was married to Hoel of Cornwall some time before 1058. Hoel exercised authority jure uxoris and continued to control the government after her death in 1072 acting as regent for their son, Alan IV. A second son, Matthew, inherited the county of Nantes.
The daughter of Alan III and Bertha de Blois, Hawise had 2 siblings Conan II and Emma of Brittany. Hawise married Hoel of Cornwall and had 3 children
-Orwen de Cornouailles, (1050-1103)
-Hildeberge de Cornouaille, (1067-1095)
-Alain IV Fergant de Cornouaille, (circa 1067- October 19, 1119) Duke of Brittany, Count of Rennes, Count of Nantes
The Duchy of Brittany was a medieval feudal state that existed between approximately 939 and 1547. Its territory covered the northwestern peninsula of Europe, bordered by the Atlantic Ocean to the west, and the English Channel to the north. It was also less definitively bordered by the river Loire to the south, and Normandy, and other French provinces, to the east. The Duchy was established after the expulsion of Viking armies from the region around 939. The Duchy, in the 10th and 11th centuries, was politically unstable, with the dukes holding only limited power outside their own personal lands. The Duchy had mixed relationships with the neighbouring Duchy of Normandy, sometimes allying itself with Normandy, and at other times, such as the Breton-Norman War, entering into open conflict.
Alan II, nicknamed Wrybeard or Twistedbeard, Alan Varvek in Breton, was Count of Vannes, Poher and Nantes, and Duke of Brittany from 938 to his death. He was the grandson of King Alan the Great by Alan's daughter and her husband Mathuedoï I, Count of Poher. He expelled the Vikings/Norsemen from Brittany after an occupation that lasted from 907 to about 939.
Odo of Rennes, Count of Penthièvre, was the youngest of the three sons of Duke Geoffrey I of Brittany and Hawise of Normandy, daughter of Richard I of Normandy. Eudon married Agnes of Cornouaille, the daughter of Alan Canhiart, Count of Cornouaille and sister of Hoel II, Duke of Brittany who was married in 1066 to Eudon's niece Hawise, Duchess of Brittany.
Alan III of Rennes was Count of Rennes and duke of Brittany, by right of succession from 1008 to his death.
Conan II of Rennes was Duke of Brittany, from 1040 to his death. Conan was the eldest child and heir of Alan III, Duke of Brittany by his wife Bertha of Blois, and member of the House of Rennes. He was the elder brother of Hawise, who succeeded him as suo jure duchess.
Hoël II was Count of Kernev, from 1058 as Hoël V. On the basis of his marriage to Hawise, Duchess of Brittany, in 1066, he became Duke of Brittany jure uxoris.
Alan IV was Duke of Brittany from 1072 until his abdication in 1112. He was also Count of Nantes and Count of Rennes. His parents were Duchess Hawise and Duke Hoel II. He is also known as Alan Fergant. Through his father, he was of the Breton House of Cornouaille dynasty. He was the last Breton-speaking Duke of Brittany.
Conan III, also known as Conan of Cornouaille and Conan the Fat was duke of Brittany, from 1112 to his death. He was the son of Duke Alan IV and Ermengarde of Anjou.
Hoèl of Cornwall was count of Nantes, from 1148 to his death. He was raised the son of Duke Conan III and Maud FitzRoy, an illegitimate daughter of King Henry I of England. However, he was disinherited by his father when on his death-bed, as Conan III claimed that Hoèl was illegitimate and no son of his. Bertha then became heiress to Duke Conan's lands in Brittany, while Hoèl was allowed to remain Count of Nantes. He was accused by St. Bernard of Clairvaux of having an incestuous affair with his sister Bertha.
Odo II, Count of Porhoet was the son of Geoffroy, Viscount de Porhoët, and his wife Hawise. He became Duke of Brittany in 1148, jure uxoris, upon his marriage to Bertha, Duchess of Brittany.
Conan IV, called the Young, was the Duke of Brittany from 1156 to 1166. He was the son of Bertha, Duchess of Brittany, and her first husband, Alan, Earl of Richmond. Conan IV was his father's heir as Earl of Richmond and his mother's heir as Duke of Brittany. Conan and his daughter Constance would be the only representatives of the House of Penthièvre to rule Brittany.
Alan, 1st Earl of Richmond, Breton Alan Penteur, also known as "Alan the Black", was a Breton noble who fought for Stephen, King of England. Alan was the third son of Stephen, Count of Tréguier, and Hawise de Guingamp.
Stephen of Penthièvre, Count of Tréguier, 3rd Lord of Richmond was a Breton noble and a younger son of Odo, Count of Penthièvre and Agnes of Cornouaille, sister of Hoël II, Duke of Brittany. In 1093, he succeeded to the title of Count of Tréguier; in 1098, he succeeded his brother Alain as Lord of Richmond in Yorkshire, England.
The counts of Nantes were originally the Frankish rulers of the Nantais under the Carolingians and eventually a capital city of the Duchy of Brittany. Their county served as a march against the Bretons of the Vannetais. Carolingian rulers would sometimes attack Brittany through the region of the Vannetais, making Nantes a strategic asset. In the mid-ninth century, the county finally fell to the Bretons and the title became a subsidiary title of the Breton rulers. The control of the title by the Breton dukes figured prominently in the history of the duchy. The County of Nantes was given to Hoel, a disinherited son of a duke. He lost the countship due to a popular uprising. That uprising presented an opportunity for King Henry II of England to attack the Breton duke. In the treaty ending their conflicts, the Breton duke awarded the county to Henry II.
The noble Breton family line of Porhoët is represented in modern times by the Franco-Breton House of Rohan.
Bertha of Cornouaille, also known as Bertha of Brittany, was hereditary Duchess of Brittany between 1148 until her death and Dowager Countess of Richmond. Bertha was the elder daughter of Conan III of Brittany by Maude, the illegitimate daughter of King Henry I of England. She was the last member of the Breton House of Cornouaille to reign over Brittany.
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. The Count of Rennes was a title held by the House of Rennes.
Hoël I of Brittany was an illegitimate son of Alan II and Judith. He was Count of Nantes and Duke of Brittany from 960 to 981.
Alain Canhiart was the count of Cornouaille from 1020 to 1058. He was the son of Benoît de Cornouaille and the father of Hoël II, Duke of Brittany. His family name, Canhiart, is understood to be derived from the old Breton Kann Yac'h and was translated into the Latin texts of his era as Bellator fortis.
Judith of Nantes was titular Countess of Nantes from 1051 to her death in 1063.