[2][a] Dehner's father was an accomplished artist who was widely recognized in the United States as a landscape painter, illustrator, and a specialist in painting "highly realistic" backgrounds for stage productions and later for animated features and shorts.

[4] Prior to the 1920s, Ella Forkum even collaborated with her husband on art projects and in some instances was co-credited for helping him to compose content for his drawings and paintings widely used in newspaper and magazine advertising.

[5] By the early 1920s, R. L. or "Roy" Forkum's growing artistic reputation earned him a commission that allowed him to take young Dehner and the rest of his family to live in Oslo, Norway while he produced illustrations for an elaborate publication celebrating the music of Norwegian composer Edvard Grieg.

[7] Following the completion of his work on the Grieg project, Roy took Ella and the children for extended stays in Stockholm, Copenhagen, London, and finally in Paris, where for two and a half years in the French capital's suburb of Asnières-sur-Seine, Dehner and his two sisters, Amy and Alice, continued their education in public schools.

Dehner's studies in France expanded his interests in art, music, and theater, as well as in the sport of fencing, in which he demonstrated sufficient skills by his early teens to qualify as a "champion" competitor.

[2][7][c] Between 1930 and 1932, "Dehner Forkum", his mother, and sisters were cited periodically in society columns in the New York Herald Tribune, which reported their attendance and personal performances at charity events, dances, music recitals, and plays presented in Hastings.

[11][12] In February 1932, as part of their high school's bicentennial celebration of George Washington's birthday, Dehner and his older sister Amy performed in Conway Cabal, a historical play written by one of their classmates.

His mother, who by then was living on Arch Street in Berkeley and managing a "variety store", chose to remain in the city while Dehner relocated to Southern California, to Los Angeles County, where in Hollywood there were greater opportunities for trained actors and artists to find employment in the film industry.

[28][29][30] After registering with the military draft in Los Angeles County in October 1940,[1] John left Disney's animation department in early March 1941 to volunteer for the U.S. Army, a full nine months before Japan attacked Pearl Harbor and officially drew the United States into World War II.

[g] Additional physical exams during routine screening for his candidacy revealed that Dehner had a stomach ulcer, one so severe that it prompted army physicians by the end of 1941 to honorably discharge him from military service on medical grounds.

[33] Dehner then moved to radio station KFWB, also broadcasting from Los Angeles, where he was part of a news team that won a Peabody Award for its reporting on the first United Nations conference held in San Francisco in 1945.

Among his earliest radio-based acting jobs was while he was employed at station KMPC, where from late 1942 to 1944 he voiced the title character and narrated the syndicated horror anthology The Hermit's Cave, which was produced by William Conrad.

[35] For the rest of the 1940s and for the remaining years of the "Golden Age of Radio", into the early 1960s, Dehner served as a guest star, a recurring character, or lead on some of the greatest nationally broadcast series of that period, all while working as well in films and on television.

[42] Although that series lasted only nine months, Dehner's representation of Kendall in 42 episodes was well received by period reviewers, one of whom described the actor's portrayal of the main character as "elegant and icily effective".

For several years he worked picture-to-picture as a modern journeyman, visiting casting offices, auditioning, and building screen time and experience at Republic, RKO, Warner Bros., Paramount, Metro-Goldwyn-Mayer, and Twentieth Century-Fox.

[45] Among Dehner's initial film appearances are his uncredited role in a Republic Western in which he broke his right hand in a fight scene and as "Sheik Ameer" in the 1943 Sol Lesser production Tarzan's Desert Mystery.

For instance, his name and roles in both Captain Eddie and State Fair are cited in the nation's top movie-fan magazine in 1945, Photoplay, as well as in The Film Daily and the Showmen's Trade Review.

Steadily during his early years of film acting, Dehner established a reputation among casting directors and theater audience as a reliable performer who could portray a myriad of characters, although most often in villainous roles as crooked gamblers, evil bankers, distinguished foreign spies, grifters, edgy gunfighters, and other "heavies".

The newspaper describes for movie fans the actor's role in an upcoming picture:HOLLYWOOD—For one of the few times in his villainous screen career, John Dehner will be seen on the right side of the law as an undercover agent in Columbia's "Counterspy Meets Scotland Yard."

Dehner, who recently completed important roles in "Last of the Buccaneers," and "Al Jennings of Oklahoma," joins a cast which includes Howard St. John, Ron Randell and Amanda Blake.

The film-industry publication Motion Picture Exhibitor, which had a large readership of theater owners in 1957, commends the overall quality of Revolt at Fort Laramie in its March 20 review but alludes to the film's lack of star power.

After appearing in three consecutive Westerns in 1970 and 1971, including Support Your Local Gunfighter with James Garner, Dehner completed his film career performing almost exclusively in productions outside the genre of "cowboy pictures".

[45][55] As Dehner's radio and film careers continued to progress in the 1950s, he also began working increasingly in the rapidly expanding medium of television, and over more than 35 years he performed on a wide range of Western series, situation comedies, science-fiction anthologies, crime dramas, made-for-TV movies, and in guest appearances on variety shows.

Some of the televised series on which he performed in the 1950s and 1960s are The Soldiers, The Real McCoys, The Andy Griffith Show, The Beverly Hillbillies, F Troop, Mission: Impossible, The Flying Nun, Get Smart, and Hogan's Heroes.

[56][57] Dehner is featured as well on the classic science-fiction series The Twilight Zone, appearing in three episodes between 1959 and 1964: as Captain Allenby, a spaceship pilot, in "The Lonely"; as Alan Richards in "The Jungle", a story about a construction-company owner who is terrorized by African spiritual forces; and as a con man, who in "Mr. Garrity and the Graves" arrives in the small 1890 town of "Happiness", Arizona claiming he can raise the dead.

Marc Scott Zicree in the 1989 edition of his book The Twilight Zone Companion highlights that quality in Dehner's portrayal of Garrity, describing the actor as "marvelously dry as a con man".

These include The Adventures of Kit Carson, Cheyenne with Clint Walker, Zorro, Maverick (four appearances in varied roles, one of which was the episode "Shady Deal at Sunny Acres" with both James Garner and Jack Kelly), Dick Powell's Zane Grey Theatre, Tales of Wells Fargo with Dale Robertson, Bat Masterson, Rawhide, Bonanza, Law of the Plainsman, The Rebel with Nick Adams, Cimarron City, The Alaskans with Roger Moore, The Restless Gun, The Rifleman, Stagecoach West, The Texan, Black Saddle, Wagon Train, Wanted: Dead or Alive, Wichita Town, Stoney Burke, A Man Called Shenandoah, Branded with Chuck Connors, The Virginian, The Wild Wild West, The Big Valley with Barbara Stanwyck, and The High Chaparral with Cameron Mitchell.

[61][62] He portrays an unlikable drifter in the televised series' second episode, "Hot Spell" (1955); an old gold miner named Nip Cullers, who is desperate to find a wife in "Tap Day for Kitty" (1956); the long-lost, devious father of Dodge City bar owner Kitty Russell in "Daddy-O" (1957); a psychotic gunman in the episode "Crack Up" (1957); a pathetic town drunk—yet a desperately protective father—in "Bottleman" (1958); a sadistic bandit in "The Badge" (1960); a lonely widower who in "The Squaw" (1961) marries a much-younger Arapaho woman and must cope with the resulting hostility of his only son; as a nomadic and lazy would-be farmer traveling with two scheming older children in "Root Down" (1962); a brain-damaged freight operator who undergoes a drastic personality change in "Ash" (1963); a dejected and childless homesteader who finds his peace in taking a bullet that saves Marshall Dillon’s life in "Caleb" (1964); a timid resident of Dodge City who gains fleeting celebrity after killing an outlaw in "The Pariah" (1965); and as Sam Wall, a ruthlessly exploitive businessman in "Dead Man's Law" (1968).

He played the part of veteran magazine editor Cy Bennett for two seasons (1971–1973) on the weekly sitcom The Doris Day Show and was cast in multiple episodes as a recurring character on other weekly series such as in the second season of the black comedy The New Temperatures Rising Show (1973), as Barrett Fears in Big Hawaii (1977), in the soap operas Bare Essence (1983) and The Colbys (1986–1987), and a return to a Western role as the "humorless, businesslike" Marshal Edge Troy in the series Young Maverick (1979–1980).

[67] Two months later, in November 1962 at the El Capitan Theatre in Hollywood, Dehner joined Lee Marvin again, along with James Whitmore, Louis Nye, and Paul Fix, to play pirates in a production of Peter Pan with Peggy Webber in the title role.