A mezzo-soprano is a female singer whose voice is a little lower than that of a soprano but not low enough to be called a contralto. There are many roles in opera that need a mezzo-soprano voice, for example the role of Carmen in the opera "Carmen" by Georges Bizet or Cherubino in "Le Nozze di Figaro" by Mozart. Famous mezzo-sopranos include: Marilyn Horne and Dame Janet Baker who have both now retired. Alice Coote and Susan Graham are famous mezzo-sopranos today.