The leader of the Civil Rights Movement who opposed segregation in the U.S. was Dr. Martin Luther King Jr. He advocated for nonviolent protest and civil disobedience as means to challenge systemic racism and promote equality. Through his leadership, King helped orchestrate significant events, such as the Montgomery Bus Boycott and the March on Washington, where he delivered his famous "I Have a Dream" speech. His commitment to justice, equality, and peaceful resistance has left an indelible mark on American history, inspiring future generations to continue the fight for civil rights and social justice.