William of Champlitte

William I Guillaume Ier
Prince of Achaea
Coat of Arms of William of Champlitte
Reign	1205-1209
Predecessor	None
Successor	Geoffrey I
Born	1160s Unknown
Died	1209 Unknown
Burial	Unknown
Spouse	Alais of Meursault Elisabeth of Mount-Saint-Jean
Issue	Unknown
Dynasty	Champlitte dynasty
Father	Odo I of Champlitte
Mother	Sybille

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).

William was the second son of Odo or Eudes I of Champlitte, viscount of Dijon (son of Hugh, Count of Champagne) and his wife, Sybille. He married first Alais, the lady of Meursault. With the consent of his wife, he donated property to the Cistercian abbey of Auberive for the soul of his younger brother, Hugh in 1196. He later married Elisabeth of Mount-Saint-Jean, but they divorced in 1199.

William and his brother, Odo II of Champlitte joined the Fourth Crusade in September 1200 at Cîteaux. 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 who had excommunicated the whole expedition after the occupation of Zara (now Zadar, Croatia). They begged the pope not to chastise Marques Boniface I of Montferrat, the leader of the crusade who had, in order to preserve the integrity of the expedition, withheld the publication of the papal bull of anathema.