John Grant Chapman (July 5, 1798 – December 10, 1856) was an American politician.
Chapman was born in La Plata, Maryland, and was tutored at home.
He studied law, was admitted to the bar in 1819, and commenced practice at Port Tobacco, Maryland.
After his tenure in Congress, Chapman resumed the practice of law at Port Tobacco, and served as president of the State constitutional convention in 1851.
He was re-interred later in Mount Rest Cemetery of La Plata, Maryland.