Duke's is a mayonnaise brand especially popular in the American South.
Eugenia Duke created the brand in Greenville, South Carolina, in 1917. She and her daughter initially sold sandwiches at Army canteens during World War I-era military training, and customer demand eventually led them to bottle and sell the mayonnaise separately.
Duke's became known for a tangy flavor and rich texture. Its traditional recipe uses more egg yolks than many competing mayonnaises, contains no added sugar, and uses apple cider vinegar. Those characteristics make it especially popular in Southern dishes such as tomato sandwiches, coleslaw, deviled eggs, pimento cheese, and potato salad.
The brand is not exclusively Southern today and is sold nationally, but its regional identity remains unusually strong. A common mix-up is assuming Duke's is simply another name for mayonnaise made by Kraft, Miracle Whip, or Hellmann's. Those are separate brands with different recipes and flavor profiles. Duke's popularity also helped make mayonnaise a fiercely debated ingredient in Southern cooking.