James Arness performed the role of Matt Dillon.
James Arness ( May 26 , 1923 -- June 3 , 2011 ) was an American actor , best known for portraying Marshal Matt Dillon for 20 years in the television series Gunsmoke . Matt Dillon is a fictional character featured on both the radio and television versions of Gunsmoke . He serves as the U.S. Marshal of Dodge City , Kansas , who works to preserve law and order in the western frontier of the 1870s .