Margaret I of Alsace (died November 15, 1194) was countess of Flanders from 1191 to her death. She ruled with her husband, count Baldwin V, Count of Hainaut, VIII of Flanders.
Margaret, however, ruled with a strong hand for many years and survived both her sons, dying at the age of eighty in 1280.
In his time the long contest between Flanders and Holland for the possession of the island of Zeeland was brought to an end by a treaty signed on the 6th of March 1323, by which West Zeeland was assigned to the count of Holland, the rest to the count of Flanders.
It was Flanders that furnished to them no small part of their resources, but for this very reason, while fostering the development of Flemish industry and trade, they were the more determined to brook no opposition which sought to place restrictions upon their authority.