Sandra Cason "Casey" Hayden (born October 31, 1937), was an American radical student activist and civil rights worker in the 1960s. Recognized for her defense of direct action in the struggle against racial segregation, in 1960 she was an early recruit to Students for a Democratic Society (SDS). With Student Nonviolent Coordinating Committee (SNCC) in Mississippi Hayden was a strategist and organizer for the 1964 Freedom Summer. In the internal discussion that followed its uncertain outcome, she clashed with the SNCC national executive.