Diamanda Galás (born August 29, 1955) is a Greek-American avant-garde composer, vocalist, pianist, performance artist and painter.
Known for her expert piano as well as her distinctive, operatic voice, which has a three and a half octave range, Galás has been described as "capable of the most unnerving vocal terror". Galás often shrieks, howls, and seems to imitate glossolalia in her performances. Her works largely concentrate on the topics of suffering, despair, condemnation, injustice and loss of dignity. She has worked with many avant-garde composers, including Iannis Xenakis, Vinko Globokar and John Zorn.