Marshall was born in London in 1890, as the only child of stage actors Percy F. Marshall and Ethel May Turner. Theatrical critics praised his father for his comic flair and “rich voice.” In addition to acting, Percy wrote and directed some plays in which he appeared. Most popular in the 1880s and 1890s, Marshall’s father retired from acting in 1922 and died on 28 December 1927 at the age of 68. Marshall later recalled: “My father was a grand actor—better than I could ever dream of being.” His mother was the sister of journalist and drama critic, Leopold Godfrey-Turner (born Leopold McClintock Turner). Marshall’s grandfather, Godfrey Wordsworth Turner, wrote several books and articles on art and travel. In an article about his love of the theatre, he noted that one of his uncles was an actor. Godfrey was also the grandnephew of influential businessman Edward Wollstonecraft, who was the nephew of women’s rights activist and author Mary Wollstonecraft and first cousin of Mary Wollstonecraft Shelley, who wrote the horror classic Frankenstein.

While his stage debut is usually listed as The Adventure of Lady Ursula (1911), some sources place it in 1909. Furthermore, Marshall remembered playing a footman alongside Eric Blore in Robert Courtneidge’s The Arcadians; his mention of Blore added an appearance in November 1910.

In 1913, he made his London debut in the role of Tommy in Brewster’s Millions. Actor-manager Cyril Maude was so impressed with his performance that he recruited Marshall for his U.S. and Canadian tour of Grumpy. When war was declared, the company returned to London, and the 24-year-old enlisted.

Marshall was married five times and divorced three. In 1914, he appeared with Mollie Maitland (whose real name was Hilda Lloyd Bosley) in The Headmaster; the following year, they were married. Five years later, he first appeared with Edna Best, who became his most frequent stage co-star; they also made three films together (The Calendar, Michael and Mary and The Faithful Heart). Marshall and Best were married in November 1928, following their respective divorces (they had been cohabiting for the previous three years). In 1931, Best broke a lucrative contract with MGM and walked off the filming of The Phantom of Paris with John Gilbert in order to be with Marshall in New York, where he was performing in a play. In response to a press inquiry, he said: “I’m sorry if Hollywood is annoyed, but Edna and I happen to be in love with each other and we want to be together.”

Marshall recalled his time on the Western Front: “I knew terrific boredom. There was no drama lying in the trenches 10 months. I must have felt fear, but I don’t remember it. I was too numb to recall any enterprise on my part.” On 9 April 1917 he was shot in the right knee by a sniper at the Second Battle of Arras in France. After a succession of operations, doctors were forced to amputate his right leg. Marshall remained hospitalised for 13 months. He later recalled in private that after his injury, he had initially over-dramatised his loss and was wrapped up in self-pity and bitterness. Before long, however, he decided he wanted to return to the theatre and learned how to walk well with a prosthetic leg in order to do so. While he was recovering at St. Thomas’ in London, King George V visited the hospital. When asked to pick which of the actor’s legs he thought was artificial, the king chose the wrong one. Throughout his career, Marshall largely managed to hide the fact that he had a prosthetic limb, although it was occasionally reported in the press.

Following the Armistice, Marshall joined Nigel Playfair’s repertory troupe, appearing in Make Believe (December 1918), The Younger Generation (1919) and Abraham Lincoln (1919). In 1920, he made his first known appearance opposite Edna Best in Brown Sugar. He also appeared in John Ferguson and the Shakespearean plays The Merchant of Venice and As You Like It. Marshall recalled “Jacques in As You Like It has given me more pleasure than any part I have played”. The following year, he toured North America with Australian star Marie Löhr and starred in A Safety Match in London. By 1922, Marshall was making regular appearances on both sides of the Atlantic, debuting on Broadway in The Voice From the Minaret and starring in Coward’s The Young Idea (with then-wife Maitland) and The Queen Was in the Parlour. Among his other successes were Aren’t We All? (1923), The Pelican (1924–25), Lavender Ladies (1925), Interference (1927–28), S.O.S. (1928) and Tomorrow and Tomorrow (1931). His greatest hits with Edna Best were the aforementioned Brown Sugar, The Charming People (1925–26), The High Road (1928–29), Michael and Mary (1930), The Swan (1930) and There’s Always Juliet (1931–32).

In 1927, Marshall debuted onscreen opposite Pauline Frederick in the British silent film Mumsie (1927). He made his first American film appearance as the lover of Jeanne Eagels’s character in the first version of The Letter (1929), produced at Paramount Pictures’ Astoria studios two years later.

The 1932 film Blonde Venus brought Marshall to fame among the general American public. Later the same year, he played Gaston Monescu, a sophisticated thief involved in a love triangle in Ernst Lubitsch’s suggestive, light comedy Trouble in Paradise (1932). In interviews, Marshall expressed a preference for playing this sort of witty comedy role. He discussed his two early films in a 1935 interview:

During a return trip to London in late November 1932, Marshall and a pregnant Best gave an interview in which they stated their intention to briefly return to Hollywood the following summer. They would bring a nanny to help look after their daughter. At some point, Best and young Sarah returned to London while Marshall received more film offers. They continued making trips to see each other. In late 1933, actress Phyllis Barry had tea with Marshall and Claudette Colbert after they returned from Hawaii, where they had been filming Four Frightened People. She remembered that Marshall “insisted on my talking all the time because he said I sounded just like his wife”. By the time Marshall was filming Riptide in early 1934, he was reportedly drinking heavily due to his problems with Best and increased phantom pain. (Director Goulding and co-star Norma Shearer successfully convinced him to curb his consumption of alcohol.) Not long after, Goulding introduced him to Gloria Swanson.

In the early 1930s, Marshall was commonly rumoured within Hollywood social circles to have had affairs with both his Trouble in Paradise co-stars Kay Francis and Miriam Hopkins. In January 1934, Marshall, while still married to Best, began a serious affair with actress Gloria Swanson, who recounted their relationship in her memoirs, Swanson on Swanson (1980). She described Marshall at the time of their first meeting as “a handsome man in his early forties with a gentle face and soft brown eyes”, who had “one of the most perfect musical voices I had ever heard”. Swanson also wrote that the actor was “sweet beyond belief” and “a nice man”, who “utterly charmed” her and her children. He constantly wrote her love notes, and when she was out of town, he sent her romantic telegrams almost hourly. (Many of these personal documents now reside at the University of Texas at Austin’s Harry Ransom Center archives, as part of the Gloria Swanson Papers.) Newspapers and film fan magazines widely discussed his affair with Swanson at the time, which he made little attempt to keep secret.

Marshall graduated from St. Mary’s College in Old Harlow, Essex and worked for a time as an accounting clerk. After being sacked for the slow speed of his calculations, he took a job as an assistant business manager of a theatre troupe run by a friend of his father’s. He later had a series of different backstage jobs at various theatres and acting companies. When a troupe he worked for reformed, he was laid off. He then tried his hand at acting. In a 1935 interview, he claimed that he only became an actor out of necessity because he did not know how to do anything else. To another reporter, he recollected how he had initially vowed never to go on the stage.

In 1936, Marshall began lending his talents to radio, appearing on such programmes as Lux Radio Theatre (at least 19 appearances), The Screen Guild Theatre (at least 16 appearances), The Jell-O Program (three appearances, including one as host), The Burns and Allen Show (two appearances), Birds Eye Open House, The Pepsodent Show and Hollywood Star Time (taking over as host in October 1946). He made radio history in July 1940 as the narrator of “The Lodger”, the first audition show of the Suspense series (making 20 appearances on the program). His most famous role was as globetrotting intelligence agent Ken Thurston in The Man Called ‘X’ (1944–52). The series, first aired on CBS as a summer replacement for the Lux Radio Theatre, introduced Thurston as an employee of an agency known only as “The Bureau”. His boss, dubbed “The Chief”, tasked him with dealing with some of the world’s most hardened, sophisticated criminals, including smugglers, murderers, black marketeers, saboteurs, kidnappers, various types of thieves, corrupt politicians and rogue scientists. Thurston’s sidekick/nemesis Egon Zellschmidt was played by character actor Hans Conried during the first season. From 1945–52, Russian comic and musician Leon Belasco appeared in the same role as Pegon Zellschmidt. The show was broadcast not only for the sake of entertainment but it also “alerted an anxious war-weary world to the inherent dangers of resting on its laurels during the brief peace after war.”

In November 1936, Swanson left him once she accepted that he would not divorce Edna Best to marry her. Although insisting they were “madly in love,” she believed that he would not demand a divorce because of his typically docile nature, reluctance to deliberately hurt people, and guilt over his separation from his young daughter. “He would always turn to alcohol rather than face a painful scene,” she remembered. Despite an emotional parting, near the end of her life Swanson, who was married six times, wrote: “I was never so convincingly and thoroughly loved as I was by Herbert Marshall.”

During the Second World War, Marshall made numerous appearances on the Armed Forces Radio Service (AFRS), hosting The Globe Theatre and guest-starring on Command Performance and Mail Call, among other programmes. He was also one of the leaders of a Hollywood British committee that helped organise the community’s contributions to British war relief. In 1940, Marshall co-starred with Rosalind Russell in Noël Coward’s Still Life (from Tonight at 8.30) at the El Capitan. The proceeds went to the British Red Cross. In 1943, he appeared briefly in the RKO film, Forever and a Day. The profits from the film funded a variety of war charities. That same year, Marshall penned a public letter of encouragement to his Hollywood colleagues serving overseas. He also performed in the short film, The Shining Future (1944), later condensed and renamed Road to Victory, which was intended to sell Canadian war bonds. Marshall and twenty-five other actors each received a plaque from a representative of the Canadian government for their participation in the film.

In 1940, after a long separation from her husband and wanting to marry someone else, Best divorced Marshall on grounds of desertion (he lived in Hollywood, while she lived in Britain). She remarried almost immediately. Twenty days later, he married actress and model Elizabeth Roberta “Lee” Russell, a sister of film star Rosalind Russell. Two years prior to their marriage, Russell’s recently divorced ex-husband, songwriter Eddy Brandt, initiated an alienation of affection suit for $250,000 against Marshall, whom he accused of stealing his wife. Brandt later told the press that he and the actor settled out of court for $10,000. Marshall publicly denied this claim. In 1947, Russell divorced him in Mexico. They parted on amiable terms. Instead of explaining the reasons for her divorce, she told the press at the time: “I will never say anything against Bart. He is one of the most charming people I have ever known.”

Beginning in 1950, Marshall performed periodically on television, starting with a production of An Inspector Calls for Robert Montgomery Presents. He was in The Ford Television Theatre. He appeared as the “mystery guest” on an episode of the popular game show What’s My Line? in November 1954.

Marshall had a daughter, Sarah, by Edna Best, and another daughter, Ann, by Lee Russell. Sarah Marshall followed her parents and grandparents into the acting profession, appearing in many of the most popular television shows of the 1960s, including Star Trek, The Twilight Zone, Perry Mason, F Troop and Daniel Boone. Herbert and Sarah Marshall acted together in a television version of J.B. Priestley’s play An Inspector Calls in 1951. His younger daughter, Ann Marshall (often called Annie), worked for many years as Jack Nicholson’s personal assistant. He also had at least four step-children, two from his marriage to Best and two from his marriage to Mallory. His grandson, Timothy M. Bourne, Sarah Marshall’s only child, is an independent film producer. Bourne was the executive producer of the Academy Award-winning film The Blind Side (2009).

With the increasing public demand for grittier films after the Second World War, the remaining members of the Hollywood British “colony” began to part ways, with some returning to Britain while others stayed in Hollywood. Marshall, like many of his contemporaries who stayed in Hollywood, began to receive far fewer acting offers and, especially toward the end of his life, had to take whatever he could get due to financial reasons. In May 1951, while in the hospital recuperating from corrective surgery, he suffered a “pulmonary embolism around his heart”. After NBC aired three episodes of The Man Called ‘X’ that were previously transcribed, Marshall’s friends Van Heflin, John Lund and Joseph Cotten filled in (one episode each) until Marshall’s return in June 1951. Marshall appeared in his last significant film role in The Caretakers (1963) with Joan Crawford, who was happy to act with him again 22 years after they made When Ladies Meet together. Noting his poor health and heavy drinking, she worked with the film’s director to minimise the time Marshall had to be on the set.

He was married to his fourth wife, former Ziegfeld girl and actress Patricia “Boots” Mallory, from 1947 until her death in 1958. They were wed in August 1947, with Nigel Bruce acting as best man. After a 16-month illness, Mallory died of a throat ailment at age 45. Marshall was deeply troubled by her death and had to be hospitalised for pneumonia and pleurisy less than two months later. He married Dee Anne Kahmann, his final wife, on 25 April 1960, when he was almost 70 years old. She was a twice-divorced, 38-year-old department store buyer. They remained married until his death.

Marshall’s final performances include the feature films College Confidential (1960), Midnight Lace (1960), A Fever in the Blood (1961), Five Weeks in a Balloon (1962), The List of Adrian Messenger (1963) and The Caretakers (1963). He guest starred on episodes of Hong Kong, Michael Shayne, Zane Grey Theater, and 77 Sunset Strip. “They don’t seem to make my kind of pictures any more,” he said in 1964.

In late 1965, after his final brief film appearance in the thriller The Third Day, Marshall was admitted to the Motion Picture Relief Fund Hospital for severe depression. Eight days after his release, he died on 22 January 1966 in Beverly Hills, California of heart failure at the age of 75.