Final answer:
Frederick Douglass was a former slave who played a crucial role in the abolitionist movement through his autobiography, speaking engagements, and influential newspaper efforts.
Step-by-step explanation:
The former slave who wrote an autobiography, started a newspaper, spoke publicly, and was an effective voice in the abolitionist movement was Frederick Douglass. After escaping from slavery, Frederick Douglass became renowned for his oratory skills and published his autobiography, Narrative of the Life of Frederick Douglass, An American Slave Written by Himself in 1845. This autobiography detailed his life as a slave in Maryland and was a critical work in African American literature, leading to Douglass fleeing the United States to avoid retaliation for his outspokenness. Besides his writing, Douglass was also a gifted speaker, drawing the attention of key figures like William Lloyd Garrison, and his advocacy significantly advanced the cause of the abolitionist movement, establishing Douglass as a leading voice for the emancipation of enslaved people.