Latin emperor of Constantinople from 1221 to 1228. He was so ineffective that the Latin Empire (consolidated by his uncle, Henry of Flanders) was largely dissolved at the end of his reign.

Robert was a younger son of Peter of Courtenay (died early 1219?) and Yolande of Flanders and Hainaut, who was empress regent for her sons until her death in September 1219. Their eldest son, Philip of Namur, refused to leave France and renounced the succession in favour of Robert, an irresponsible youth, who was crowned in Constantinople on March 25, 1221. Robert was betrothed to Eudocia, daughter of the Greek emperor at Nicaea, Theodore I Lascaris. In 1225 Theodore's successor, John III Vatatzes (John III Ducas Vatatzes), forced Robert to cede most of the eastern lands of his Latin Empire in Asia Minor, and by 1228 Theodore Angelus, ruler of Epirus, a city-state in Asia Minor, seized Thessalonica and was crowned emperor there. In the meantime Robert had repudiated Eudocia and taken a French mistress, who was mutilated in the ensuing revolt by Robert's own barons. He died while fleeing to take refuge with Pope Gregory IX.

Robert was born into a family of knights. Arriving in Apulia, in southern Italy, around 1047 to join his half brother Drogo, he found that it and Campania, though they were southern Italy's most flourishing regions, were plagued by political disturbances. These regions attracted hordes of fortune-seeking Norman immigrants, who were to transform the political role of both regions in the following decades.

In Campania, the Lombards of Capua were launching wars against the Byzantine (Byzantine Empire) dukes of Naples in order to gain possession of that important seaport. In Apulia, William (William de Hauteville) (“Iron Arm”) de Hauteville, Robert's eldest half brother, having successfully defeated the Byzantine Greeks who controlled that region, had been elected count of Apulia (Puglia) in 1042. In 1046 he had been succeeded by his brother Drogo.

When Robert joined his brothers, they sent him to Calabria to attack Byzantine territory. He began his campaign by pillaging the countryside and ransoming its people. In 1053, at the head of the combined forces of Normans from Apulia and Campania, he defeated the haphazardly led forces of the Byzantines, the Lombards (Lombard), and the papacy at Civitate. Because of the deaths of William and Drogo and of his third half brother, Count Humphrey, in 1057, Robert returned to Apulia to seize control from Humphrey's sons and save the region from disgregating internal conflicts. After becoming the recognized leader of the Apulian Normans, Robert resumed his campaign in Calabria. His brother Roger's (Roger I) arrival from Normandy enabled him to extend and solidify his conquests in Apulia.

In his progression from gang leader to commander of mercenary troops to conqueror, Robert emerged as a shrewd and perspicacious political figure. In 1059 he entered into a concordat at Melfi with Pope Nicholas II. Until that time the papacy had been hostile toward the Normans, considering them to be an anarchist force that upset the political structure in southern Italy—a structure based on a balance of power between the Byzantines and the Lombards of northern Italy. The schism that took place between the Greek and Latin churches in 1054 temporarily worsened the relations between the Byzantine emperors and the papacy, and eventually the papacy realized that Norman conquests over the Byzantines could work to its advantage. Robert's plan to expel the Arabs from Sicily and restore Christianity to the island also found favour in Nicholas' eyes. This expedition into Sicily got under way in 1060, as soon as the conquest of Calabria was completed. Robert entrusted the command of the expedition to his brother Roger, but on particularly difficult occasions—e.g., the siege of Palermo in 1071—he came to his brother's aid.

Until this time, Robert's relations with Roger had not always been amicable, since Roger, aware of both his own talent and Robert's dependency on him, would not settle for the subordinate role allotted him. Their differences were resolved when Robert invested Roger, after he had recognized Robert's supreme authority, with “the County of Sicily and Calabria” along with the right to govern and tax both counties.

Robert continued to expand the small county left by Humphrey into a duchy, extending from the Adriatic to the Tyrrhenian sea. The capture of Bari in April 1071 resulted in the end of Byzantine rule in southern Italy. Robert turned next to the neighbouring territories of Salerno, controlled by the Lombards. Instead of fighting them, he dissolved his first marriage and in 1058 married the sister of Salerno's last Lombard prince, Gisulf II (Gisulph II). Hostilities broke out between the two rulers, however, and Gisulf naively tried to bring about a Byzantine counteroffensive against Robert. Fearing that the Norman advances into Campania, Molise, and Abruzzi would threaten the papal dominions, Pope Gregory VII (Gregory VII, Saint) excommunicated Robert and gave Gisulf considerable military aid. The struggle came to a head when Gisulf, determined to display his power, advanced toward the prosperous city of Amalfi. Robert responded to the city's plea for help in 1073 and successfully defended it; in December 1076 he took Salerno from Gisulf and made it the capital of his duchy.

Robert was now at the height of his power. During his rise he repressed with an iron hand not only the claims of Humphrey's sons but also the uprisings of towns and lords that were fretting under the restraints imposed upon them. The harshness with which Robert chose to deal with these rebels was intended to transform a heterogeneous population into a strong state.

When, in 1080, the conflict between church and state over the right to control ecclesiastical personnel and property had become more intense, Robert chose to reconcile himself with Gregory VII, entering into the Concordat of Ceprano, which confirmed the commitments of the earlier Council of Melfi. Even the Byzantine court drew closer to him and went as far as trying to establish a familial relationship with Robert. The Byzantine emperor Michael VII (Michael VII Ducas), in need of Robert's help to uphold his unstable throne, married his son, Constantine, to one of Robert's daughters, Helen. The opposition party, however, deposed Michael and confined Helen in a monastery. To guarantee Apulia against attack from the new rulers of Byzantium, Robert wanted the territories on the Adriatic coast of the Balkan (Balkans) Peninsula, and he began to build a large navy. Michael's expulsion and Helen's confinement reawakened his unappeased spirit of adventure and hastened his long-considered expedition. Now his goal was even more ambitious: to march to Byzantium and crown himself emperor in place of the deposed Michael.

In 1083 Robert landed in Epirus with a well-trained army and immediately succeeded in defeating the Byzantines and their Venetian allies. The pope, however, suddenly recalled him to Italy to help him expel the German king Henry IV, who was marching on Rome en route to claiming southern Italy for the Holy Roman Empire. Having returned home and suppressed the revolts of the lords hostile to himself and to Pope Gregory VII, Robert moved toward Rome, defeated the pope's enemies, and escorted him to Salerno in the summer of 1084. Following this success, he returned to his campaign on the Adriatic coast. He died during the siege of Cephalonia on July 17, 1085.

Physically attractive, endowed with an acute and unscrupulous intelligence, a brilliant strategist and competent statesman, Robert had begun to organize a state composed of diverse ethnic and civil groups: Latin and Germanic in Lombard territories and Greek in Byzantine domains. The new political structure was built on a monarchial-feudal framework characteristic of the time, but it was controlled by the energetic and uncompromising Robert, who tried to use his ducal power to create a powerful and prosperous state. The other base on which he built was Latin Christianity, the religion of the conquerors and most of the conquered, which he used to reconcile the subjected peoples. An extremely religious man, Robert was distrustful of the Greek clergy because of their ties with Byzantium. On the other hand, his generosity toward the Latin church was bountiful. He endowed it with territories and clerical immunities in order to tie it firmly to himself. Splendid cathedrals and Benedictine abbeys were built in the hope that they would consolidate and diffuse Latin language and culture among the heterogeneous people and tie them into a new, unified state.

Angevin prince and Guelf (papal party) leader who ruled Naples as king for 34 years (1309–43).

Robert's early years were clouded by the War of the Sicilian Vespers (1282–88), in which his father, Charles II of Anjou, was taken prisoner by the Aragonese. By the terms of the treaty Charles was freed, and Robert took his place as hostage at the Aragonese court. Taking the title of duke of Calabria (1296), he led an expedition attempting to recover Sicily from the Aragonese prince who ruled it as Frederick III. Robert's military success produced the Peace of Caltabellotta (1302), by which the Aragonese agreed to return Sicily to the House of Anjou when Frederick died.

On the death of his father in 1309, Robert inherited Naples and extensive territories in northern Italy and southern France. For several years Robert skirmished politically and militarily on the side of the Guelf party in northern Italy against the Ghibelline (pro-imperial) faction led by the Visconti of Milan, whom he defeated at Sesto, west of Genoa, in 1319. His desire to enlist the interest of Pope John XXII in a final defeat of the Ghibellines of northern Italy caused Robert to take up residence at Avignon, the papal seat, but in 1324 the victory of the Visconti over Guelf forces at Vaprio, east of Milan, brought him back to Italy to defend his lands.

Robert remained neutral when the German king Louis the Bavarian marched into Italy, was crowned emperor in Rome as Louis IV (1328), and set up an antipope, Nicholas V. Relations between Robert and John XXII terminated when the Pope allied himself with King John of Bohemia, who invaded northern Italy in 1330. In return for King John's support, the Pope offered him Robert's territories in southern France. The Pope's diplomacy shattered the traditional Guelf–Ghibelline alignments in Italy, and the league that Robert joined, consisting of members of both parties, drove King John out of Italy in 1336. The final years of Robert's reign were marked by defections of his northern Italian towns, and his failure to regain Sicily after Frederick III's death in 1337 brought a steady decline of Angevin power and influence.