Thurgood Marshall was a lawyer and civil rights activist who became the first African American to serve as an Associate Justice of the Supreme Court of the United States. Before his judicial service, he successfully argued several cases before the Supreme Court, including Brown v. Board of Education, which ruled that racial segregation in public schools was unconstitutional. As founder-director of the NAACP Legal Defense and Educational Fund, Marshall played a crucial role in dismantling legal segregation in the United States.