Guy II de la Roche was the Duke of Athens from 1287, the last duke of his family. He succeeded as a minor on the death of his father, William I, at a time when the duchy of Athens had exceeded the Principality of Achaea in wealth, power, and importance.
Guy was originally under the tutorship and regency of his mother, Helena Angelina Komnene, who was forced to make submission to Isabella of Villehardouin in December 1289. In 1291, she married her second husband, Hugh of Brienne, and he became bailiff of the duchy. Guy reached his majority in 1296 and did homage to Isabella and her husband, Florent of Hainaut. In 1299, Guy was engaged to Matilda, daughter of Isabella and Florent. Charles objected, as his permission had not been sought, but Pope Boniface VIII intervened on the young couple's behalf.
When Guy did homage to Isabella's second husband, Philip of Savoy, in 1301, he took his troops with him and entered Thessaly to defend his cousin John II Doukas against the invasion of the despot of Epirus, Thomas I Komnenos Doukas, and his mother, Anna Palaiologina Kantakouzene. Joined by Nicholas III of St Omer, lord of Thebes, he repulsed the Epirotes and later invaded Greek territory as far as Thessalonica, where they were convinced to turn back by the empress Eirene of Montferrat.
In 1307, Guy was made bailli of Achaea by its new prince, Philip I of Taranto. He governed well, but for barely a year. He died, 5 October 1308, at the age of twenty-eight, but was respected and renowned for his chivalry and manners, typical of the Frankish courts kept in Greece. He was buried in Daphni Monastery alongside his ancestors. He left no heirs and the De la Roche line of dukes came to an end; Athens was disputed among rival claimants until the parliament of the duchy elected Walter V of Brienne.