(Born May 26, 1923) James Arness is an actor best known for portraying Marshal Matt Dillon on Gunsmoke for 20 years, a record length for a character on a single prime time show (though the length of time in a role is shared with Kelsey Grammer's portrayal of Dr. Frasier Crane, Grammer played the same role on three different programs, Cheers, Frasier, and Wings). Arness is the older brother of actor Peter Graves.