He was finally transferred to the United States Marine Corps as a radio operator and shipped out to the South Pacific shortly before the war ended.

Having one year remaining on his GI Bill benefits, he studied drama at the University of Southern California, where he pursued a master's degree in theater history.

[2][10] Parker began his show-business career in the summer of 1951 when he had a $32-a-week job as an extra in the play Mister Roberts,[10] although he is credited with the voice of Leslie the chauffeur in the 1950 film Harvey.

Parker became a contract player with Warner Bros., appearing in small roles in several films such as Springfield Rifle (1952), Island in the Sky, The Bounty Hunter, and Battle Cry.

Parker had recently graduated to being a contract weekly actor but listened to his agent and appeared in a Warner Bros. science fiction film about giant ants called Them!, which required only one day's work.

[11] Parker became a contract star for Disney and appeared in The Great Locomotive Chase, Westward Ho, the Wagons!, Old Yeller, and The Light in the Forest.

He performed the occasional role of Tom Conrad, editor of the Diablo Courier in the syndicated western series, Annie Oakley (1954–1957), starring Gail Davis, Brad Johnson, and Jimmy Hawkins.

He appeared in a small assortment of Paramount movies, including a cameo as an unnamed frontiersman in Bob Hope's Western comedy Alias Jesse James and supporting roles in The Hangman (1959) with Robert Taylor, The Jayhawkers!

In 1962, he starred in the title role of the TV series Mr Smith Goes to Washington, portraying the same idealistic character that James Stewart had played in the 1939 film.

Parker's Daniel Boone television series portraying another historic figure of America's frontier days began filming in 1964.

[17][18] For his work with Disney, Parker was honored in December 2004 with his own tribute window on a façade in the Frontierland section of Disneyland.

[23][24] The Parker operation includes over 1,500 acres (610 ha) of vineyards, and a tasting room and visitor center along the Foxen Canyon Wine Trail.

In addition to wine, the winery is known for selling coonskin caps and bottle toppers inspired by Parker's Crockett and Boone characters, and for its appearance under another name in the movie Sideways.

[25] In 1985, Parker briefly flirted with running in 1986 for the United States Senate as a Republican for the seat of incumbent Democrat Alan Cranston.