Graham cracker refers to a type of cracker that was originated by Rev. Sylvester Graham, a Presbyterian minister, in the early 1800s as a "health food". It was originally made solely with whole-wheat flour, but many modern imitiation Graham crackers contain no whole-wheat flour at all, and are based on bleached, refined white flour, which the Rev. Graham implacably opposed. Reverend Graham termed the unsifted whole-wheat flour he used Graham flour.

His original "Graham bread" was made with the intent of supressing carnal urges, which he believed were the source of many maladies (He also warned that ketchup and mustard caused insanity).

Graham crackers have long since ceased to be considered a health food, but they have remained popular as a snack food. Today, graham crackers are made with much greater amounts of sugar and other sweeteners than used in the original recipe. Cinnamon is also commonly added to graham cracker mix to enhance the flavor.

Graham crackers are essential ingredients for various popular snack foods, including moon pies and s'mores.

See also: Digestive biscuit