Sylvester Graham (July 5, 1794 - September 11, 1851) was an American reformer notable for his invention of Graham crackers.

Born in Suffield, Connecticut, he was ordained as a Presbyterian minister in 1826, but turned out not to be suited to that life style. He was a keen student of healthy living and the vegetarian diet, and in 1829 he invented a food article from unsifted flour which was then called "Graham bread". This item continues to be popular as "Graham crackers" or "Graham biscuits".

Graham developed a significant following of grahamites in response to his eloquent lectures and writings. To the temperance movement he offered a vegetarian diet as a cure for alcoholism. He also advocated sexual restraint and bathing.

In 1837 he had difficulty finding a place to speak in Boston because of threatened riots by butchers because he preached strict vegetarianism, and by bakers because he advocated home baking and avoidance of commercially produced nutritionless white breads.

In 1850 he helped to found the American Vegetarian Society modeled on a similar organization established in Great Britain three years earlier.

He died in Northampton, Massachusetts the following year.