Jon Hassell (born March 22, 1937) is an American trumpet player and composer active since the 1960s. He is best known for developing the musical concept Fourth World, which describes a "unified primitive/futurist sound" combining elements of various world ethnic traditions with modern electronic techniques. The concept was first articulated on Fourth World, Vol. 1: Possible Musics, his 1980 collaboration with Brian Eno. He has also worked with artists such as the Theatre of Eternal Music, Talking Heads, Farafina, Peter Gabriel, Ani DiFranco, Techno Animal, and Ry Cooder.