Alfred Lewin Copley (1910–1992) was a German-American medical scientist and an artist at the New York School in the 1950s. As an artist he worked under the name L. Alcopley. He is best known as an artist for his abstract expressionist paintings, and as a scientist for his work in the field of hemorheology. He was married to the Icelandic artist Nína Tryggvadóttir.
As a scientist, Copley studied the rheology of blood. In 1948 he introduced the word biorheology to describe rheology in biological systems. In 1952 he introduced the word hemorheology, to describe the study of the way blood and blood vessels function as part of the living organism. In 1966 he established the International Society of Hemorheology, which changed its name and scope in 1969 to the International Society of Biorheology (ISB). In 1972 the ISB awarded him its Poiseuille gold medal.
In 1949 he was one of twenty artists who founded the Eighth Street Club. The group also included Franz Kline, Willem de Kooning and Alcopley's close friend, the composer Edgard Varèse.
He participated in the Ninth Street Show in 1952 and had a solo exhibition at the Stedelijk Museum, Amsterdam in 1962. His work is held in the collection of the National Museum of Modern Art, Tokyo.