Constance Guiscard (1127-1163) was the ruler of the principality of Antioch (a crusader state) from 1130 to her death.

Constance was the only daughter of Bohemund II of Antioch by his wife Alice, princess of Jerusalem. She became princess of Antioch with only four years old, under the regency of Baldwin II of Jerusalem (1130-1131) and Fulk of Jerusalem (1131-1136). Her mother Alice did not want the principality to pass to Constance, preferring to rule in her own name. Alice attempted to ally with the Muslim atabeg of Mosul, Zengi, offering to marry Constance to a Muslim prince, but the plan was foiled by Alice's father Baldwin, who exiled her from Antioch. In 1135 Alice attempted once again to take control of the principality, and sought a husband for Constance in Manuel Comnenus, at that time the heir to the Byzantine throne. Fulk exiled her again and re-established the regency for Constance. In 1136, while still a child, Constance was married to Raymond of Poitiers, whom the noble supporters of the regency had secretly summoned from Europe; Alice was tricked into believing Raymond was going to marry her, and, humiliated, left Antioch for good when the marriage was performed. From this union three children were born:

• Bohemund III of Antioch, who succeeded her in 1163
• Mary of Antioch (1145-1182), married (rechristened as "Xena") to Manuel I Comnenus
• Philippa of Antioch, married to Andronicus I Comnenus

In 1149, Raymond died in the battle of Inab and Constance remarried in 1153 to Raynald of Chatillon, who also became co-ruler of Antioch. Constance had two daughters from Raynald:

• Agnes (1154-1184), married king Bela III of Hungary
• Alice, married Azzo V d'Este