LOS ANGELES (Reuter) - Actor Robert Mitchum, the sleepy- -eyed, barrel-chested star of more than 125 films that spanned six decades, died early on Tuesday. He was 79. Mitchum died in his sleep at his home in Santa Barbara around 5 a.m. PDT (1200 GMT), according to his agent, Jack Gilardi. Mitchum had been suffering from emphysema for more than a year and was diagnosed with lung cancer last spring. He had an image in Hollywood as a "bad boy", which was fuelled by a 1948 arrest for marijuana possession, which led to six months in a work camp. His workmanlike approach to his craft grew from an unstable past. Born on Aug. 6, 1917, in Bridgeport, Connecticut, he was soon left fatherless and led a gypsy-like childhood, frequently moving, always struggling. As a young man in the 1930s, he wandered the country and the world, working as an engine wiper on a freighter, a nightclub bouncer, a boxer, a ditchdigger and a publicist for an astrologer. In 1940 he married his high school sweetheart, Dorothy Spence, and settled down to raising a family and working for a California aircraft company. Unhappy there, he signed on as an extra in "pictures," as he always called movies. Appearances in Westerns led to bit parts in a string of "B" movies and two big war films, "Cry Havoc" and "Gung Ho!," both released in 1943, a year in which he appeared in 18 films. In 1945 Mitchum made the big time as the rugged but weary captain of "The Story of GI Joe," based on the war memoirs of war correspondent Ernie Pyle. The role earned Mitchum an Academy Award nomination for best supporting actor, but he did not show up at the ceremony. In 1947, he starred in one of his best Westerns, playing a heroic stranger in "Blood on the Moon." Hits and misses followed through the 1960s. Successes included "The Sundowners" (1960), "Cape Fear" (1962) and "El Dorado" (1967). In 1975 he was brilliantly cast as the laconic detective Philip Marlowe in a remake of Raymond Chandler's "Farewell My Lovely," a role he repeated in 1978 in "The Big Sleep." In 1980 Mitchum reversed his stand against television and agreed to do a TV movie, the 16--hour miniseries "The Winds of War." In 1991 he appeared in Martin Scorsese's remake of "Cape Fear", with Robert De Niro and Nick Nolte. Despite brief separations in 1948 and 1953, Mitchum remained married to his wife Dorothy. Of their three children, his sons James and Christopher have occasionally acted and his daughter Petrine, worked for a movie production company.