Early career

MacArthur's first radio role was on the Theatre Guild on the Air in 1948, accompanying his mother Helen Hayes.

MacArthur made his stage debut in Olney, Maryland in 1949 with a two-week stint in The Corn Is Green. His sister Mary, who was also in the play, had requested that he join the company. The following summer, he repeated the role in Dennis, Massachusetts and his theatrical career was under way.^[1]

In 1954, he played John Day in Life with Father with Howard Lindsay and Dorothy Stickney. He became involved in important Broadway productions only after receiving his training in summer-stock theater. He worked as a set painter, lighting director and chief of the parking lot. During a Helen Hayes festival at the Falmouth Playhouse on Cape Cod, he had a few walk-on parts. He also helped the theater's electrician and became so interested that he was allowed to remain after his mother's plays had ended. As a result, he lit the show for Barbara Bel Geddes in The Little Hut and for Gloria Vanderbilt in The Swan.^[3][4]

Television

In 1955, at the age of 18, MacArthur played Hal Ditmar in the television play '"Deal a Blow", an episode of the series Climax! directed by John Frankenheimer and starring Macdonald Carey, Phyllis Thaxter and Edward Arnold. The critical response was excellent, with the New York Times saying that he "performed splendidly."^[5]

The following year, Frankenheimer directed the film version of the play, which was renamed The Young Stranger (1957), with MacArthur again in the starring role. His performance was again critically acclaimed, earning him a nomination for Most Promising Newcomer at the 1958 BAFTA awards.^[6]

In late 1956, it was announced that MacArthur would make Underdog, based on a novel by W. R. Burnett, along with his mother and Susan Strasberg, but the project never materialized.^[7]

MacArthur returned to television to appear in World in White (1957) and episodes of General Electric Theater, Studio One in Hollywood and Westinghouse Desilu Playhouse.

Disney

MacArthur was selected by Walt Disney to star in The Light in the Forest (1958), playing a white man raised by Indians. In April 1957, he signed a three-picture deal with Disney. For Light in the Forest he was paid $2,500 per week, which increased to $3,000 per week for the second film and $3,500 for the third. However, MacArthur was only available to work during his summer vacation from Harvard, where he was studying history.^[8]

Disney executives liked his performance and cast him in Third Man on the Mountain (1959), playing a young man who climbs the Matterhorn. His mother had a cameo role.^[9]

Deciding to make acting his full-time career, he left Harvard in his second year to appear in two more Disney movies, Kidnapped (1960) and Swiss Family Robinson (1960). He was named a possibility for Bon Voyage (1962) but did not appear in the film.^[10]

MacArthur made his Broadway debut in 1960 playing opposite Jane Fonda in Invitation to a March, for which he received a Theatre World Award. Although he never returned to Broadway, he remained active in theater throughout his career, appearing in such productions as Under the Yum Yum Tree, The Moon Is Blue, John Loves Mary (with his wife Joyce Bulifant), Barefoot in the Park and Murder at the Howard Johnson's.^[11]

He also released several records in the early 1960s,^[12] scoring two minor hits with "(The Story of) The In-Between Years" and "The Ten Commandments of Love", which peaked at number 94 on the Billboard Hot 100 in 1963.^[2]

MacArthur delivered a chilling performance as baby-faced opium dealer Johnny Lubin in The Untouchables episode "Death For Sale". He also appeared in episodes of the television shows Bus Stop and Wagon Train. He returned to feature films as one of several young actors in The Interns (1962), Columbia's popular medical drama.

He appeared in episodes of The Dick Powell Theatre, Sam Benedict and Arrest and Trial, then made Spencer's Mountain (1963) at Warner Bros. with Henry Fonda and Cry of Battle (1963) in the Philippines.^[13]

In 1963, MacArthur was nominated for the Top New Male Personality category of the Golden Laurel Awards. That year, he starred in and produced a pilot for a television series about a writer, Postmark: Jim Fletcher, but it was not sold.^[13]

He guest-starred on the television shows Burke's Law, The Eleventh Hour and The Great Adventure, The Alfred Hitchcock Hour before appearing in the feature films The Truth About Spring and The Bedford Incident, both in 1965.

In Battle of the Bulge (1965), MacArthur again played the role of a young and inexperienced officer. He appeared in Ride Beyond Vengeance (1966) and guest-starred on Branded, Combat!, Gunsmoke, Hondo, Insight, Death Valley Days, Bonanza, The Virginian, Twelve O'Clock High and Tarzan.

MacArthur returned to Disney to appear in Willie and the Yank (1967) for television, released theatrically as Mosby's Marauders. He also had a role in The Love-Ins (1967) for Sam Katzman^[14] and a brief but memorable appearance in the Clint Eastwood film Hang 'Em High (1968) as a preacher.

Hawaii Five-O

Hang 'Em High was written by Leonard Freeman, who was producing a new police procedural, Hawaii Five-O. Tim O'Kelly was originally cast as Jack Lord's assistant, but test audiences felt that he was too young, so MacArthur was offered the role.^[1] MacArthur said that Lord "said 'book him' to others in the cast, but I guess he said it to me the most. It wasn't anything we really thought about at first. But the phrase just took off and caught the public's imagination."^[1]

Appearing in the show made MacArthur wealthy,^[15] and he invested much of his earnings in Hawaiian real estate.^[1]

MacArthur left the show in 1979, feeling that it had become bland and predictable. It was canceled one year later. He later reflected: "It was just time. I called the producer from South America and told him I was heading down the Amazon River."^[16][17]

William Smith, who replaced him on the show, claimed that MacArthur quit "because Jack Lord wouldn't let him have a dressing room. He had to change in the prop truck for eleven years."^[18]

After Hawaii Five-O

After leaving Hawaii Five-O, McArthur guest-starred on television shows such as Time Express, Murder, She Wrote, The Love Boat, Fantasy Island, Walking Tall, The Littlest Hobo,Vega$ and Superboy. He also appeared in the miniseries Alcatraz: The Whole Shocking Story (1980) and The Night the Bridge Fell Down (1983).^[19] He returned to the stage, appearing in A Bedfull of Foreigners in Chicago in 1984 and in Michigan in 1985. He followed this with The Hasty Heart before taking a year out of showbusiness.

In 1987, he again took to the stage in The Foreigner, and then played Mortimer in the national tour of Arsenic and Old Lace. In 1989, he followed another stint in The Foreigner with Love Letters and in 1990–1991, A Bedfull of Foreigners in Las Vegas.

Semi-retirement

From 1959 to 1960, MacArthur partnered with actors James Franciscus and Alan Ladd, Jr. in the ownership of a Beverly Hills telephone-answering service. In June 1972, he directed the Honolulu Community Theatre in a production of his father's play The Front Page.

He appeared at conventions, collectors' shows and celebrity sporting events. A keen golfer, he won the 2002 Frank Sinatra Celebrity Invitational Golf Tournament.

MacArthur also appeared in television and radio specials and on interview programs such as Entertainment Tonight, Christopher's Closeup and the BBC Radio 5 Live obituary program Brief Lives, in which he paid tribute to his Hawaii Five-O castmate Kam Fong. In 1997, MacArthur returned without Jack Lord (who was in declining health) to reprise his character, who had become Hawaii's governor, in the 1997 unaired reboot pilot of Hawaii Five-O.

In April 2003, he traveled to Honolulu's historic Hawaii Theatre for a cameo role in Joe Moore's play Dirty Laundry. Negotiations were under way in Summer 2010 for MacArthur to make a cameo appearance in the new CBS primetime remake of Hawaii Five-O at the time of his death, a role that eventually was offered to Al Harrington. Before the start of the November 1, 2010 episode, MacArthur's death was mentioned in a short tribute.

In 2001, a Golden Palm Star on the Palm Springs Walk of Stars was dedicated to MacArthur.^[20]