Marij Julij Kogoj was a Slovenian composer and writer of Italian birth. He is noted for his expressionist music, including the opera Črne maske (Black Masks), work that was well received in 1920s Slovenia amid a flowering of avant-garde artistic, cultural, and political movements. As a young man, he studied with Franz Schreker and then Arnold Schoenberg. In 1932, schizophrenia ended his career prematurely. His music and milieu is receiving renewed attention in the 21st century, but he remains little known internationally.