Eva Ortiz (born January 11, 1961), better known as Eva O, is a music artist most notable for her previous works in Christian Death and a band she formed with her then-husband Rozz Williams called Shadow Project. Regarded as a veteran and "one of the most striking figures of the American Gothic scene," Eva O has had a significant influence on the emerging deathrock movement, which garnered her the "Queen of Darkness" title from the press and audience. She is known for her heavy guitar playing style and dramatic, authoritative vocals.

She now releases solo albums with her band Mz O and Her Guns, as well as having recently joined a variation of Christian Death (known as Christian Death 1334) with original members and while she takes on vocal duties in place of the late Rozz Williams.