The influential civil rights activist who sued for desegregation in education was Thurgood Marshall. As chief counsel for the NAACP, he argued the pivotal case of Brown v. Board of Education in 1954, challenging the constitutionality of racial segregation in public schools. Marshall’s efforts led to the Supreme Court declaring that "separate but equal" educational facilities were inherently unequal, paving the way for the civil rights movement and significant progress towards racial equality in the United States.