FAIR-HAIRED, wide-grinned and easy-going, Eddie Albert played the amiable sidekick in numerous Hollywood movies, winning the first of two Oscar nominations as Gregory Peck’s pal in Roman Holiday (1953). In the United States he was best known as the New York lawyer who goes to live in the country in the television series Green Acres (1965-71), which was screened on the BBC in the UK. But he was not restricted to comedy and light drama and delivered powerful performances as the cowardly officer in Robert Aldrich’s classic war film Attack (1956) and as the sadistic prison warden in another Aldrich film, The Mean Machine (1974), with Burt Reynolds as the former professional footballer.

Eddie Albert was more than a Hollywood character actor; he was also a great Hollywood character. He originally signed to a seven-year contract with Warner Brothers., but his early career suddenly stalled. It was rumoured that Jack Warner discovered he was having an affair with his wife and refused to cast him in any further films, but would not release him from his contract so he could not work for any other company.

Albert responded by signing up as a clown and trapeze artist in a small circus in Mexico, where he reported on Nazi activity for the US Government. After Pearl Harbor, he enlisted in the navy and served with distinction in the Pacific. He resumed his film career after the war, campaigned on environmental issues long before it became fashionable, spent time with the missionary, doctor and humanitarian Albert Schweitzer in the Congo in the 1950s and turned the front garden of his home in Pacific Palisades, California, into a cornfield and travelled the world promoting awareness of humanitarian issues. Although he suffered from Alzheimer’s disease, he kept active and was playing basketball, in a wheelchair, with his granddaughter just days before his death.

He was born Edward Albert Heimberger in Rock Island, Illinois, in 1906. Reference books give his year of birth as 1908, but his actor son Eddie Albert Jr, said that his father’s mother was unmarried when he was born and she subsequently amended his birth certificate for the sake of respectability. He grew up largely in Minneapolis where he discovered a talent for entertaining. Dropping out of university, he toured as part of a singing trio, dispensing with his surname because radio announcers kept calling him Eddie Hamburger. He also had ambitions as an actor and appeared on Broadway in Brother Rat (1936-37), a comedy set in a military academy, and The Boys from Syracuse (1938-39), the Rodgers and Hart musical based on Shakespeare’s A Comedy of Errors.

A 1938 film version of Brother Rat gave him his start in movies, alongside Ronald Reagan and Jane Wyman. Over the next five years he starred in no fewer than sixteen.

During the Second World War he distinguished himself at the Battle of Tarawa, braving heavy enemy fire to rescue injured Marines. He received the Bronze Star. In 1945 he married the Mexican actress Margo and the marriage lasted till her death 40 years later. While in the navy he had been involved in training films, and he set up his own company making industrial and educational films, including controversial sex education films for children.

He also returned to acting, working initially for smaller studios, such as Republic. “I took everything they could throw at me,” he told one interviewer, “pictures like The Dude Goes West and The Fuller Brush Girl. I worked myself back up, but I never wanted to be a star. I was aiming to play the star’s best friend.”

He worked with William Wyler on the romantic drama Carrie (1952) and again on Roman Holiday (1953), with Gregory Peck and Audrey Hepburn. He filled the colourful role of the Persian salesman Ali Hakim in the musical Oklahoma! (1955), he was an army psychiatrist in The Teahouse of the August Moon (1956), and the American expatriate Bill Gorton in The Sun Also Rises (1957), alongside Errol Flynn.

Albert and Flynn were swiftly reunited on John Huston’s African adventure The Roots of Heaven (1958), which was shot in Chad and, like so many of Huston’s films, was beset with problems. Albert found the location shoot and separation from Margo particularly difficult. Huston recalled in his autobiography: “Eddie Albert began to worry because he wasn’t getting any word from his wife . . . Eddie was a family man. He just couldn’t accept the fact that he was in the heart of Africa, where the principal means of communication was by drum. I passed his tent one night and heard muffled sobbing. I went in and tried to comfort him, but he was utterly distracted. Shortly after that he contracted an ‘affliction’ in his legs. He could stand; but to get to the bathroom he had to hang from a pole carried aloft by two bearers.”

Other films included The Joker is Wild (1957); the all-star war movie The Longest Day (1962); John Ford’s 7 Women (1966), in which he played a missionary; the Neil Simon comedy The Heartbreak Kid (1972), which brought him his second Oscar nomination for his performance as Cybill Shepherd’s exasperated father; and McQ (1974), in which he and John Wayne were police officers.

As well as appearing in films, Albert worked regularly in television from the late 1940s onwards. Green Acres was a spin-off from another sitcom, Petticoat Junction, and was set in the farming community of Hooterville, where Albert and his wife Eva Gabor take over a rundown farm. It reflected Albert’s keen interest in the environment.

He is survived by a son and an adopted daughter.

Eddie Albert, actor, was born on April 22, 1906. He died on May 26, 2005, aged 99.