Jefferson Davis was the first President of the Confederate States of America from 1861 to 1865. He was also a Representative, Secretary of War, and Senator for the United States prior to this.
Stan appeared dressed as Davis in the "The Red Badge of Gayness", in order to end the Civil War reenactment.
Jefferson Davis was never drawn like his celebrity likeness and instead appeared in the form of Stan Marsh dressing up as him. Stan simply wore a black tuxedo with a white shirt, and a black vest. Stan also wore a wig, similar style to Davis' actual hair style, over his red poofball hat.