Contraltos are the lowest female singers commonly heard. Unlike their male counterparts (the basses), however, roles for altos are a bit more common, especially in rock musicals. In more traditional pieces, altos are frequently middle-aged leading women, though some of those are mezzos as well. The only role demographic altos have a firm hold over is for women over sixty - which in most shows means grandmothers. In the rare case that there is a female villain in a show, she will probably be an alto.
“Raven hair and ruby lips, sparks fly from her finger tips, Echoed voices in the night, she’s a restless spirit on an endless flight. Wooo hooo witchy woman, see how high she flies." (Pt. 1:X)(Pt: 2: X)(Pt: 3: X)