Maria Constanze Cäcilia Josepha Johanna Aloysia Mozart (née Weber) (5 January 1762 – 6 March 1842) was a trained Austrian singer. She married twice. Her first husband was Wolfgang Amadeus Mozart; her second husband was Georg Nikolaus von Nissen. She and Mozart had six children: Karl Thomas Mozart, Franz Xaver Wolfgang Mozart, and four others who died in infancy. She became Mozart's biographer jointly with her second husband.