Colonel Sartoris is the mayor of Jefferson and is best described as a typical southern gentleman-- which has its good and bad points. On the good side, he helps Emily by not making her pay taxes he knows she cannot afford. On the other hand, he says that "no Negro woman should appear on the streets without an apron."
Sartoris appears in other works by Faulkner as well, he is an important character in Faulkner's body of work, and his third novel is entitled /Sartoris/.
Colonel Sartoris is a former mayor of the town. In 1894 he established the idea (myth?) that the town had to take care of her, and specifically that she didn't have to pay taxes. He is no longer alive, and left no record of his reasoning for later generations to follow.