Robert II (died 1156) was the count of Aversa and the prince of Capua from 1127 until his death .
He was the only son and successor of Jordan II of Capua. According to the Lombard chronicler Falco of Benevento, he was "of delicate constitution, he could endure neither labour nor hardship."
In the final month of 1127, Pope Honorius II came to Benevento to preach a crusade against Count Roger II of Sicily in order to prevent the union of his county with the duchy of Apulia (Duke William II being recently deceased). At the start of 1128, Honorius II granted investiture to Robert which made the principalities of Capua independent from Apulia. The pope endeavoured to gain Robert's loyalty to help defeat Roger II of Sicily in return for remissions of his sins. He was quickly recruited for the endeavour by the pope, who went to Capua for the ceremony. The pope probably hoped to use Capua as a counterpoise against Apulia, as in the days of Robert's grandfather and great grandfather. Likewise, Robert may have intended to be the chief papal protector, as his ancestors had been. However, he was weak-willed and he soon fell ill and wanted out. Eventually, the coalition commenced negotiations on Roger's arrival with an army. Honorius even successfully negotiated the independence of Capua. In 1129, however, Robert submissively surrendered suzerainty to the duke of Apulia and, the next year (on 25 December 1130) it was believed by Falco of Benevento that, as Roger's vassal-in-chief, laid the crown on his head at his royal coronation. This is difficult to believe as it was such a crucial role and Roger II would not have wanted Robert, as one of his vassals, to perform such an important task, even if he was one of the highest rank.
In 1132, Robert rebelled with many other south Italian vassals of the king of Sicily and with the support of Pope Innocent II and his coalition of Louis VI of France, Henry I of England, and the Emperor Lothair II. Robert defeated Roger at the Battle of Nocera on 24 July, but Roger burnt Aversa and, by 1134, forced Ranulf, count of Alife, and the nominally Byzantine Duke Sergius VII of Naples to submit. Robert was given an ultimatum; if he wanted to keep his title, he must submit to Roger. After the death of Roger's wife, Elvira, and the false news of Roger's death, Robert went to Naples from Pisa with 8000 men. He was met by Rainulf and Duke Sergius when Roger arrived in June 1135, he again offered Robert a choice to keep his title. Roger made his third son Alfonso prince in his stead (1135).