William I of Champlitte (French: Guillaume de Champlitte) (1160s-1209) was a French knight who joined the Fourth Crusade and became the first prince of Achaea (1205–1209).

[1][2][3] William was the second son of Odo or Eudes I of Champlitte, viscount of Dijon.

William was one of the crusader leaders who signed the letter written in April 1203 by Counts Baldwin IX of Flanders, Louis I of Blois and Chartres and Hugh IV of Saint Pol to Pope Innocent III after the occupation of Zara (now Zadar, Croatia).

[5] Early in 1205 Geoffrey of Villehardouin, one of William of Champlitte's allies went to the camp of Boniface I of Thessalonica at Nauplia (now Nafplion, Greece).

[6] William in short time occupied Coron (now Koroni, Greece), Kalamata and Kyparissia.