Constantine Bodin (Serbian: Konstantin Bodin, Константин Бодин; Bulgarian: Константин Бодин), was a king of Duklja (1081–1101), and for a short time in 1072 he was emperor (tsar) of Bulgaria by name Peter III (Bulgarian: Пeтър III, Petăr III). The date of his birth is unknown; that of his death is uncertain, and may be as late as 1108.
In 1072 the Bulgarian noblemen in Skopje raised a revolt against Byzantine rule under the leadership of George Voitekh (Georgi Vojteh), a descendant of the former Bulgarian court nobility. The rebels asked King Michael I of Zeta to provide one of his sons, as descendants of the House of the Kometopouloi, to assume the Bulgarian throne.
In the fall of 1072 Constantine Bodin, Michael's seventh son, arrived in Prizren with a small retinue of Zetan troops and met with George Voitekh and other representatives of the Bulgarian nobility. They escorted him to Skopje and crowned him emperor of the Bulgarians under the name Peter III, recalling the names of the sainted Emperor Peter I (Petăr I, who had died in 970) and of Peter II Delyan (Petăr II Deljan, who had led the first major revolt against Byzantine rule in 1040–1041).
The troops of the newly-crowned Peter III took Niš and Ohrid, but suffered a crippling defeat in front of Kastoria. The Byzantine counter-attack took Skopje with the help of George Voitekh, who betrayed first Peter III, and then attempted to betray the Byzantines, but in vain. In another battle Peter III was taken captive by the Byzantines and sent, together with George Voitekh, as prisoner to Constantinople. George Voitekh died en route, while the former Peter III languished in prison first at Constantinople and then at Antioch.
In about 1078 Venetian sailors rescued Constantine Bodin from captivity and returned him to his father Michael I of Duklja. Shortly afterwards, in 1081, Michael died, and Constantine Bodin succeeded his father as king.
By 1085, he and his brothers had suppressed a revolt by their cousins, the sons of Michael's brother Radoslav in the župa of Zeta, and Constantine Bodin ruled unchallenged. In spite of his earlier opposition to the Byzantine Empire, Constantine Bodin at first supported the Byzantines against the attack of Robert Guiscard and his Norman on Durazzo in 1081, but then stood idle, allowing the Normans to take the city.
At about this time, Constantine Bodin married the daughter of a pro-Norman nobleman from Bari. Constantine Bodin's relations with the west included his support for Pope Urban II in 1089, which secured him a major concession, the upgrading of his Bishop of Bar to the rank of an Archbishop.
Constantine Bodin attempted to maintain the enlarged realm left him by his father. To do so, he campaigned in Bosnia and Raška, installing his nephews Marko and Vukan as župans in the latter. The two princes were sons of Constantine Bodin's half-brother Petrislav, who had governed Raška in about 1060–1074. However, after the death of Robert Guiscard in 1085, Constantine Bodin was faced by the hostility of the Byzantine Empire, which recovered Durazzo and prepared to punish the king of Duklja for siding with the Normans.
The Byzantine campaign against Duklja is dated between 1089 and 1091 and may have succeeded in taking Constantine Bodin captive for the second time. Although the kingdom survived, outlying territories including Bosnia, Raška, and Hum (Zahumlje) seceded under their own governors. Exactly what happened in Duklja is unknown, and there may have been a civil war during Constantine Bodin's possible captivity. Queen Jakvinta ruthlessly persecuted possible claimants to the throne, including Constantine Bodin's cousin Branislav and his family. After a number of these persons were killed or exiled by Constantine Bodin and his wife, the church managed to keep the impending blood feud from sparking off a full-blown civil war.
On Constantine Bodin's death in 1101 or possibly 1108, Duklja was engulfed in the conflict caused by the dynastic strife that had begun to develop during his reign.