Dame Isoleen Heather Begg DNZM OBE (1 December 1932 – 12 May 2009) was a New Zealand-born operatic mezzo-soprano who spent most of her career in the United Kingdom and Australia. She was renowned in roles such as the title role in Bizet's Carmen, Amneris in Verdi's Aida and in lighter operas such as The Gondoliers. She appeared alongside Dame Joan Sutherland, Luciano Pavarotti, Beverly Sills, Dame Kiri Te Kanawa, Plácido Domingo, Montserrat Caballé, Dame Janet Baker, José Carreras, Dame Malvina Major, Sir Donald McIntyre and many other prominent singers. Her recording with Glenys Fowles of the "Flower Duet" from Delibes's Lakmé has become famous.
Born in Nelson, New Zealand in 1932, Begg studied in Auckland with Sister Mary Leo and at the New South Wales State Conservatorium, during which time she won the 1955 Sydney Sun Aria contest. She was engaged as a principal mezzo-soprano with the National Opera of Australia from 1954-56. Her professional debut was as Azucena in Verdi's Il trovatore.