American composer, violinist, sometime rocker, and the theorist who coined the term "concept art" in an article written in 1961. He defined it as "art of which the material is 'concepts, as the material of for ex. music is sound". This is the first written definition of what later became known as Conceptualism. Also he was associated with Fluxus. Friend of both La Monte Young and George Maciunas. He contributed above article to one of the first proto Fluxus document called, An Anthology which was edited by Young and Jackson MacLow and typeset by Maciunas.

He studied Indian Classical Music from Pandit Pran Nath.

He also wrote, "Blueprint For a Higher Civilization"

During his Fluxus years Henry did a lot of Performance Art, including with Yoko Ono, George Brecht, Dick Higgins and George Maciunas.