The Widow Clicquot, or Madame Barbe-Nicole Clicquot, was the pioneering woman who took over the Veuve Clicquot Champagne house after her husband's death in 1805. She is important because she revolutionized the Champagne industry with innovations like the riddling table and the creation of vintage Champagne, transforming Veuve Clicquot into a world-renowned brand.