Marie of Champagne (c. 1174 – 9 August 1204) was the Empress consort of Baldwin I of Constantinople.
She was a daughter of Henry I, Count of Champagne and Marie of France, Countess of Champagne. Her maternal grandparents were Louis VII of France and Eleanor of Aquitaine.
Her brothers were Henry II of Champagne and Theobald III, Count of Champagne. Her sister Scholastique of Champagne married William V of Macon. Both sisters are mentioned by name in the chronicle of Alberic of Trois-Fontaines.
According to the chronicle of Gislebert of Mons, Marie was bethrothed to "Theobald", son of the count of Flanders and Hainaut in 1179. Gislebert is presumed to have misrecorded the name of Baldwin. Her betrothed was Baldwin VI, son of Baldwin V, Count of Hainaut and Margaret I, Countess of Flanders.
On 6 January 1186, Marie and Baldwin were married. They had two known children:
Joan, Countess of Flanders (1199/1200 – 5 December 1244).
Margaret II, Countess of Flanders (2 June 1202 – 10 February 1280).
On 14 April 1202 her husband left Flanders to join the Fourth Crusade. This Crusade was diverted to Constantinople, capital of the Byzantine Empire. The crusaders captured and sacked the city. Then they decided to set up a Latin Empire in place of the fallen Greek one. On 9 May 1204, Baldwin was elected its first emperor making Marie the empress consort.
Marie herself left Flanders to join her husband but decided to visit Outremer first. According to Geoffrey of Villehardouin she could not join him in the crusade earlier as she was pregnant at the time of his departure. After delivery of the child, Margaret and sufficient recovery, she set forth to join him.
She set sail from the port of Marseille and landed in Acre. There she received tribute by Bohemond IV of Antioch. In Acre news reached her of the fall of Constantinople and the proclamation of Baldwin as the new emperor. She wanted to set sail for Constantinople but fell sick and died in the Holy Land.
News of her death reached Constantinople through Crusading reinforcements from Syria. Baldwin was reportedly afflicted by the death of his wife. Villehardouin reports that Marie "was a gracious and virtuous lady and greatly honored".