Gunsmoke is an American radio and television Western drama series created by director Norman Macdonnell and writer John Meston. The stories take place in and around Dodge City, Kansas, during the settlement of the American West. The central character is lawman Marshal Matt Dillon, played by William Conrad on radio and James Arness on television. When aired in the UK, the television series was initially titled Gun Law, later reverting to Gunsmoke.

The radio series ran from 1952 to 1961. John Dunning wrote that among radio drama enthusiasts, "Gunsmoke is routinely placed among the best shows of any kind and any time." The television series ran for 20 seasons from 1955 to 1975, and stands as America's longest-running prime time, live-action drama with 635 episodes. In 2010, Law & Order tied Gunsmoke for most seasons for a live action drama series when it finished its 20th and final season, but the show finished 179 episodes short of Gunsmoke's final total; in terms of prime-time scripted series with continuing characters, The Simpsons is the only program to exceed 20 seasons. At the end of its run in 1975, Los Angeles Times columnist Cecil Smith wrote: "Gunsmoke was the dramatization of the American epic legend of the west. Our own Iliad and Odyssey, created from standard elements of the dime novel and the pulp western as romanticized by [Ned] Buntline, [Bret] Harte, and [Mark] Twain. It was ever the stuff of legend."

In the late 1940s, CBS chairman William S. Paley, a fan of the Philip Marlowe radio serial, asked his programming chief, Hubell Robinson, to develop a hardboiled Western series, a show about a "Philip Marlowe of the Old West". Robinson instructed his West Coast CBS Vice President, Harry Ackerman, who had developed the Philip Marlowe series, to take on the task.

Ackerman and his scriptwriters, Mort Fine and David Friedkin, created an audition script called "Mark Dillon Goes to Gouge Eye" based on one of their Michael Shayne radio scripts, "The Crooked Wheel". Two auditions were created in 1949. The first was very much like a hardboiled detective series and starred Michael Rye (credited as Rye Billsbury) as Dillon; the second starred Straight Arrow actor Howard Culver in a more Western, lighter version of the same script. CBS liked the Culver version better, and Ackerman was told to proceed.

A complication arose, though; Culver's contract as the star of Straight Arrow would not allow him to do another Western series. The project was shelved for three years, when producer Norman Macdonnell and writer John Meston discovered it while creating an adult Western series of their own.

Macdonnell and Meston wanted to create a radio Western for adults, in contrast to the prevailing juvenile fare such as The Lone Ranger and The Cisco Kid. Gunsmoke was set in Dodge City, Kansas, during the thriving cattle days of the 1870s. Dunning notes, "The show drew critical acclaim for unprecedented realism."

The radio series first aired on CBS on April 26, 1952 with the episode "Billy the Kid", written by Walter Newman, and ended on June 18, 1961. The show stars William Conrad as Marshal Matt Dillon, Howard McNear as Doc Charles Adams, Georgia Ellis as Kitty Russell, and Parley Baer as Dillon's assistant, Chester Wesley Proudfoot.