While the exact year is unknown, the hair straightener dates back to at least 1872. At this time, a Parisian named Marcel Grateau was using heated combs or rods to curl and straighten hair. Straightening combs began to appear in Sears and Bloomingdale's catalogs in the 1880s.
While the person who invented hair straighteners is unknown, Madam C.J. Walker is credited with teaching African-American women how to use the hot comb to straighten their hair. She also invented a line of hair care products specifically for African-American women in 1905. In doing so, she became one of the first American women to be considered a self-made millionaire.