Galás has been described as "capable of the most unnerving vocal terror", with her three and a half octave vocal range. Her works largely concentrate on the topics of AIDS, mental illness, despair, injustice, condemnation, and loss of dignity. She has worked with many avant-garde composers, including Iannis Xenakis, Vinko Globokar and John Zorn, and also collaborated with jazz musician Bobby Bradford, and John Paul Jones, former bassist of Led Zeppelin.
Diamanda Galás was born and raised in San Diego, California, to Greek Orthodox parents. She studied a wide range of musical forms, and played gigs in San Diego with her father, also a musician, performing Greek and Arabic music. After moving to Europe, Galas made her solo performance debut at the Festival d'Avignon, in France, in 1979, performing the lead in the opera Un Jour comme un autre, by composer Vinko Globokar, based upon Amnesty International's documentation of the arrest and torture of a Turkish woman for alleged treason.
Galás' first album was The Litanies of Satan, released in 1982. Her second album, Diamanda Galas, was released in 1984.
Diamanda Galás' work first garnered widespread attention with The Masque of the Red Death, an operatic trilogy which includes The Divine Punishment, Saint of the Pit and You Must Be Certain of the Devil. In it, she details the suffering of people with AIDS. Shortly after the recording of the trilogy's first volume began, her brother, playwright Philip-Dimitri Galás, became sick with the disease, which goaded Galás to redouble her efforts. Philip-Dimitri Galás died in 1986, just before the completion of the trilogy.