Well harriet tubman was a good read and I'm not sure who it's written by. Zhao is also a very good writer and she is considered the African American writer.
Lorraine Hansberry is probably the most famous. She wrote the play Raisen in the Sun which was made into a Broadway production in 1959. Harriet Jacobs is also famous for writing a slave narrative.
For novels, you can't go wrong with Toni Morrison. Some of her best works are Beloved and Sula. For poetry, Maya Angelou is a favorite as well as Nikki Giovanni.
One of the most popular and earliest African-American writers is Philis Wheatley. Other popular African-American female writers include Lorraine Hansberry, Ntozake Shange, and Maya Angelou.