Maria Callas was a Greek-American opera singer and one of the most renowned and influential opera singers of the 20th century. She is best known for her roles in operas such as 'NORMA', 'Medea' and 'Ariadne auf Naxos'. Her vocal range was a SOPRANO, and she was often referred to as a DIVA due to her powerful and emotive performances. She also sang arias from many other operas, including 'La Traviata' and 'Tosca'.