Robert Wagner was born in Detroit, and his family moved to Los Angeles when he was seven. Always wanting to be an actor, he held a variety of jobs (including one as a caddy for Clark Gable while pursuing his goal, but it was while dining with his parents at a restaurant in Beverly Hils that he was "discovered" by a talent scout. He had a bit part in The Happy Years (1950) but it was a small part as a crippled soldier in the Susan Hayward film With a Song in My Heart (1952) that got him attention. His fresh, all-American looks landed him a contract with 20th Century-Fox, which put him in a succession of undemanding roles in Technicolor pictures where his looks were more important than his talent (Beneath the 12-Mile Reef (1953), Prince Valiant (1954)), but he did manage to show that he was indeed an actor of talent in several showy roles in smaller pictures (A Kiss Before Dying (1956), Between Heaven and Hell (1956)). As he became one of Fox's rising young stars, the studio, as was customary back then, set him up with a host of nubile young actresses, among them Debbie Reynolds. While the pairing didn't lead to any romance, it did lead to a lifelong friendship.
In 1957 Wagner fell in love with 18 year old actress Natalie Wood and they married later that year on December 28. However, the marriage was short-lived, lasting just three years. Wagner had a supporting role in The War Lover (1962), and went to Europe to make the movie The Longest Day (1962). In Europe he met with his old friend Marion Marshall. They began a romance, and married on July 22, 1963. He helped raise her two sons by director Stanley Donen. On May 11, 1964, the couple had a daughter, Katie Wagner. For the first several years, R.J. and Marion seemed to be very happy, but Wagner's lagging career put stress on the marriage. In 1968 he reluctantly went into television to star in "It Takes a Thief" (1968) (later he would say it was the right move). The series lasted two years before ending in 1970. Wagner briefly returned to the big screen opposite Paul Newman in Winning (1969). Wagner's career seemed to be thriving, but his personal life wasn't. He and Marion went their separate ways and divorced in 1971 after nearly a decade together.
Over the next two years Wagner struggled to find work. In 1971 he became engaged to Tina Sinatra, but they ended their engagement in January 1972. Just six months later, on July 16, 1972, he remarried Natalie Wood after a brief reunion. On March 9, 1974, they had a daughter, Courtney Wagner. Wagner went on to appear in the blockbuster "disaster film" The Towering Inferno (1974), starring Paul Newman, Steve McQueen, and Faye Dunaway. He also starred in two successful television series. The first was the police show "Switch" (1975) with Eddie Albert, and the series lasted three years before its cancellation in 1978. The second was playing Stefanie Powers' husband in the hit "Hart to Hart" (1979)), which would run for five years. His professional and personal lives seemed to be right on track. Then on November 29, 1981, Natalie drowned in a freak boating accident. Shortly after, at the beginning of 1982, Wagner began a relationship with actress Jill St. John, whom he had first met in the 1950s when he was an up-and-coming actor and she (like Wood) was a teenage starlet. Wagner starred in Curse of the Pink Panther (1983), and had another TV series, "Lime Street" (1985), which was short-lived. He and Jill finally married on May 26, 1990 after eight years together.
Wagner has since revived his career as the eye-patch-wearing henchman Number Two to Mike Myers' sinister Dr. Evil in the spy spoofs Austin Powers: International Man of Mystery (1997), Austin Powers: The Spy Who Shagged Me (1999), and Austin Powers in Goldmember (2002). He also became the hose of Fox Movie Channel's "Hour of Stars" (1955), which shows recently discovered and restored episodes of the old TV anthology series "The 20th Century-Fox Hour" (1955), some of which Wagner himself had starred in. In 2008 he began a recurring role on the hit sitcom "Two and a Half Men" (2003). Later that year he published his autobiography "Pieces of My Heart."