Abstract Expressionist and Lyrical Abstraction painter and Color Field artist associated with the Washington Color School. He conceived the idea of the "unsupported canvas" in 1965 and revolutionized the perception of the blank canvas.
He attended the University of Louisville, where he held his first exhibition in 1955. He was enlisted in the United States Army from 1956 until 1958.
He was the seventh of eight children born to Sam and Estery Gilliam. He married journalist Dorothy Butler in 1962.
He was a contemporary of Frank Stella.