The famous anti-slavery activist who authored "The Narrative of the Life of Frederick Douglass" is Frederick Douglass himself. Born into slavery, Douglass escaped and became a leading figure in the abolitionist movement. His autobiographical work, published in 1845, provided a powerful firsthand account of the horrors of slavery, advocating for human rights and social justice. Douglass’s eloquence and intellectual prowess challenged prevailing racial stereotypes, making him a key speaker and writer in the fight against slavery. He continued to advocate for equality and civil rights until his death, leaving a lasting influence on American society.