Robert, called "The Magnificent" (French, "le Magnifique") for his love of finery, and also called "The Devil" was the son of Duke Richard II of Normandy and Judith, daughter of Conan I, Duke of Brittany.
When his father died, his elder brother Richard succeeded, whilst he became Count of Hiémois. When Richard died a year later, there were great suspicions that Robert had Richard murdered, hence his other nickname, "Robert le diable" (the devil). He is often mis-identified with the legendary Robert the Devil. Robert aided King Henry I of France against Henry's rebellious brother and mother, and for his help he was given the territory of the Vexin. He also intervened in the affairs of Flanders, supported Edward the Confessor, who was then in exile at Robert's court, and sponsored monastic reform in Normandy.
By his mistress, Herleva of Falaise, he was father of two children:
the future William the Conqueror (1028-1087).
Adelaide of Normandy (1030-c.1083), who was married three times:
Enguerrand II, Count of Ponthieu
Lambert II, Count of Lens
Odo II of Champagne
After making his illegitimate son William his heir, he set out on pilgrimage to Jerusalem. According to the Gesta Normannorum Ducum he travelled by way of Constantinople, reached Jerusalem, and died on the return journey at Nicaea on 2 July 1035. Some sources attribute his death to poison and date it to 1 or 3 July. His son William, aged about eight, succeeded him.
According to the historian William of Malmesbury, around 1086 William sent a mission to Constantinople and Nicaea, charging with bringing his father's body back to be buried in Normandy. Permission was granted, but, having travelled as far as Apulia (Italy) on the return journey, the envoys learned that William himself had meanwhile died. They then decided to re-inter Robert's body in Italy.