It's possible you are thinking of:
* Sambo: A slave who is owned by the O'Hara family and serves as a loyal companion to the children, particularly to Scarlett. He is a beloved and important character in the novel and film, though his name is often portrayed as "Sam" in the film due to the changing racial sensitivities in the 20th century.
* "Mammy:" The O'Hara family's head cook and housekeeper, who is a strong and authoritative figure in the novel and film. Her name is sometimes misremembered as "Sam" due to the character's gender-neutral nature.
If you can remember any other details about this character you are thinking of, I might be able to help you identify them further.