The famous civil rights activist known for her pivotal role in the Montgomery Bus Boycott is Rosa Parks. On December 1, 1955, Parks famously refused to give up her seat to a white passenger, violating segregation laws. Her arrest ignited a 381-day boycott of the Montgomery bus system, organized by leaders like Martin Luther King Jr.. This protest became a crucial turning point in the American civil rights movement, emphasizing the struggle for racial equality and justice. Parks' courageous act and subsequent activism continue to inspire generations advocating for social justice in various forms.