Mary Johnson (March 29, 1898 or 1900 – July 20, 1983) was an American classic female blues singer, accordionist and songwriter. Her most noted tracks are "Dream Daddy Blues" and "Western Union Blues." She wrote several of the songs she recorded, including "Barrel House Flat Blues", "Key to the Mountain Blues" and "Black Men Blues." Johnson worked with Peetie Wheatstraw, Tampa Red, Kokomo Arnold and Roosevelt Sykes, among others. She was married to the blues musician Lonnie Johnson.