Diane Judith Nash (born May 15, 1938) is an American civil rights activist and strategist of the student wing of the Civil Rights Movement. Nash's campaigns were among the most successful of the era. Her efforts included becoming the chairman of the Nashville Student Movement; organizing the Nashville sit-ins, the first successful civil rights campaign to integrate lunch counters; continuing the Freedom Rides, which desegregated interstate travel; co-founding the Student Nonviolent Coordinating Committee (SNCC); and co-initiated the Alabama Voting Rights Project and working on the Selma Voting Rights Movement with her husband, James Bevel.

Their Selma campaign helped gain Congressional passage of the Voting Rights Act of 1965, which authorized the federal government to oversee and enforce state practices to ensure that African Americans and other minorities were not prevented from registering and voting. In July 2022, Nash was awarded the Presidential Medal of Freedom by President Joe Biden.

Nash was born in May 1938 and raised Catholic in a middle-class family in Chicago by her father Leon Nash and her mother Dorothy Bolton Nash. Her father was a veteran of World War II. Her mother worked as a keypunch operator during the war, leaving Nash in the care of her grandmother, Carrie Bolton, until age seven. Carrie Bolton was a cultured woman, known for her refinement and manners. After the war, Nash's parents' marriage ended. Dorothy married again to John Baker, a waiter on the railroad dining cars owned by the Pullman Company. Baker was a member of the Brotherhood of Sleeping Car Porters, one of the most powerful black unions in the nation.

As Dorothy no longer worked outside the house, Diane saw less of her grandmother Carrie Bolton. Nonetheless, Bolton continued to be an important influence on Nash's life and was committed to making sure Diane understood her value. Bolton didn't discuss race often, believing that racial prejudice was taught to younger generations by their elders. Her grandmother's words and actions instilled in Diane confidence and a strong sense of self-worth. Simultaneously, her grandmother's influence cultivated a sheltered environment that left her vulnerable to the severity of racism in the outside world.

Nash attended Catholic schools, and at one point considered becoming a nun. She also was the runner-up in a regional beauty pageant leading to the competition for Miss Illinois. After graduating from Hyde Park Academy High School in Chicago, Nash went to Washington, D.C., to attend Howard University, a historically black college (HBCU). After a year, she transferred to Fisk University in Nashville, Tennessee, where she majored in English. Nash acknowledged that she looked forward to personal growth during her time in college and wanted to explore the challenging issues of the time.

In Nashville, she was first exposed to the full force of Jim Crow laws and customs and their effect on the lives of Blacks. Nash recounted her experience at the Tennessee State Fair when she had to use the "Colored Women" restroom, signifying the first time she had ever seen and been impacted by segregation signage. Outraged by the realities of segregation, Nash began to show signs of leadership and soon became a full-time activist. Nash's family members were shocked when she joined the Civil Rights Movement. Her grandmother was quoted as saying, "Diane, you've gotten in with the wrong bunch"; she did not know that Diane was the chairwoman of organizing the nonviolent protests at her university. Her family was not familiar with the idea of working for civil rights, and it took her family time to fully recognize her position as a key player in the Civil Rights Movement. Her mother soon became a supporter by fundraising for the Freedom Riders. Nash said in a PBS Tavis Smiley interview, "My mother ended up going to fundraisers [in Chicago that sent money to] white students in the South and, [she even went] to an elevated train bus station one day at 6:00 a.m. to hand out leaflets protesting the war." Her mother was influenced by Nash's sense of empowerment.

At Fisk, Nash searched for a way to challenge segregation. Nash began attending nonviolent civil disobedience workshops led by James Lawson. While in India, James Lawson had studied Mahatma Gandhi's techniques of nonviolent direct action and passive resistance used in his political movement. By the end of her first semester at Fisk, Nash had become one of Lawson's most devoted disciples. Although originally a reluctant participant in nonviolence, Nash emerged as a leader due to her well-spoken, composed manner when speaking to the authorities and to the press. In 1960 at age 22, she became the leader of the Nashville sit-ins, which lasted from February to May. Lawson's workshops included simulations in order to prepare the students to handle verbal and physical harassment that they would ultimately face during the sit-ins. In preparation, the students would venture out to segregated stores and restaurants, doing nothing more than speaking with the manager when they were refused service. Lawson graded their interactions in each simulation and sit-in, reminding them to have love and compassion for their harassers. This movement was unique for the time in that it was led by and composed primarily of college students and young people. The Nashville sit-ins spread to 69 cities across the United States.

Though protests would continue in Nashville and across the South, Nash and three other students were first successfully served at the Post House Restaurant on March 17, 1960. Students continued the sit-ins at segregated lunch counters for months, accepting arrest in line with nonviolent principles. Nash, with John Lewis, led the protesters in a policy of refusing to pay bail. In February 1961, Nash served jail time in solidarity with the "Rock Hill Nine" — nine students imprisoned after a lunch counter sit-in. They were all sentenced to pay a $50 fine for sitting at a whites-only lunch counter. Chosen as spokesperson, Nash said to the judge, "We feel that if we pay these fines we would be contributing to and supporting the injustice and immoral practices that have been performed in the arrest and conviction of the defendants." When Nash asked Nashville's mayor, Ben West, on the steps of City Hall, "Do you feel it is wrong to discriminate against a person solely on the basis of their race or color?", the mayor admitted that he did. Three weeks later, the lunch counters of Nashville were serving blacks. Reflecting on this event, Nash said, "I have a lot of respect for the way he responded. He didn't have to respond the way he did. He said that he felt it was wrong for citizens of Nashville to be discriminated against at the lunch counters solely on the basis of the color of their skin. That was the turning point. That day was very important." In August 1961, Nash participated in a picket line to protest a local supermarket's refusal to hire blacks. When local white youths started egging the picket line and punching various people, police intervened. They arrested 15 people, only five of whom were the white attackers. All but one of the blacks who were jailed accepted the $5 bail and were freed. But Nash stayed. The 23-year-old activist had insisted on her arrest with the other blacks, and once in jail, refused bail.