Abernathy, Ralph David ăb´ərnăth˝ē [key], 1926–90, American civil-rights leader, b. Linden, Ala. A Baptist minister, he helped Martin Luther King , Jr., organize the Montgomery bus boycott (1955). He was treasurer, vice president, and, after Kings assassination (1968), president of the Southern Christian Leadership Conference (SCLC). An advocate of nonviolence as a means to social change, he led the Poor Peoples Campaign on Washington, D.C., after Kings death. He resigned from the SCLC in 1977.