Ellen Louise Demorest (née Curtis, November 15, 1824 – August 10, 1898) was an American businesswoman, fashion arbiter and milliner, widely credited for inventing mass-produced tissue-paper dressmaking patterns. With her husband, William Jennings Demorest, she established a company to sell the patterns, which were adaptations of the latest French fashions, and a magazine to promote them in 1860. Her dressmaking patterns made French styles accessible to ordinary women, thus greatly influencing US fashion.