William I de la Roche

William I de la Roche (died 1287) succeeded his brother, John I, as Duke of Athens in 1280.

William reversed the territorial losses of his brother's reign, extending his control over Lamia and Gardiki.

He married Helena Angelina Komnene, daughter of John I Doukas, ruler of Thessaly, securing a military alliance with him.

William built the castle of Dimatra to defend Messenia from the Byzantine Empire.

William's rule was peaceful but short, as he died two years after assuming power in Achaea (1287).