Simplify the following text for a Grade 8 native English-speaking person.
Original: He is best known for the The Autobiography of Malcolm X , which he helped Malcolm X write , and his book Roots : The Saga of an American Family , which was about his family history and inspired a television mini-series .
Simplified: He is best known as the author of Roots : The Saga of an American Family and the co-author of The Autobiography of Malcolm X.