Diamanda Galás (born August 29, 1955) is an American musician, singer-songwriter, and visual artist. She has campaigned for AIDS education and the rights of the infected.

Galás's commitment to addressing social issues and her involvement in collective action has made her concentrate on themes such as AIDS, mental illness, despair, loss of dignity, political injustice, historical revisionism, and war crimes. Galás has attracted the attention of the press particularly for her voice – a soprano sfogato – and written accounts that describe her work as original and thought-provoking refer to her as "capable of the most unnerving vocal terror", an "aesthetic revolutionary", "a mourner for the world's victims" and "an envoy of risk, honesty and commitment".

As a composer, pianist, organist and performance artist, Galás has presented mainly her own work, but her live performances have also included works by other musicians, such as the avant-garde composers Iannis Xenakis and Vinko Globokar, jazz musician Bobby Bradford, saxophonist John Zorn, and Led Zeppelin bassist John Paul Jones. Galás's recordings have also included collaborations, some of which are with the bands Recoil and Erasure, instrumentalist Barry Adamson, and musician Can Oral (also known as Khan), among others.