Larry Hagman is best known for his role as J.R. Ewing, the unscrupulous heir to a Texas oil fortune, in the long-running Dallas, the blockbuster night-time soap opera that still defines the genre. Less well known is the actor's earlier work in a variety of media.

The son of musical star Mary Martin, Hagman moved to England as a member of the cast of his mother's stage hit South Pacific after a variety of early theatrical experiences. He remained in England for five years, producing and directing shows for U.S. servicemen, before returning to the United States and appearing in a series of Broadway and off-Broadway plays.

Hagman's first television experience began with various guest appearances on such shows as Playhouse 90. He was then cast in the daytime soap opera The Edge of Night, in which he appeared for several years. In 1965, he became a television star playing Major Tony Nelson, astronaut and "master" to a beautiful blonde genie, in the comedy series/ Dream of Jeannie, which ran from 1965 to 1970. He subsequently appeared in The Good Life and Here We Go Again and was a frequent guest star on a variety of television programs, until undertaking the career-making role of the crafty, silkily charming villain J.R. Ewing in 1978.

Hagman's role as the ruthless good old boy of Southfork would become indelibly associated with American cultural and economic life of the early 1980s. Over the course of 330 episodes, Dallas featured an American family beset by internal problems, many originating in the duplicitous schemes of its central figure, J.R. Ewing, who was a far cry from television's previous patriarchs. Viewers who tuned in could expect a weekly dose of greed, family feuds, deceptions, bribery, blackmail, alcoholism, adultery, and nervous breakdowns in the program that became, for a time, the second-longest-running dramatic hour in prime-time history (after Gunsmoke). The show's blended themes of sex, power, and money also sold well worldwide. When J.R. was shot in March 1980, the audience totaled 300 million in 57 countries.

Particularly noteworthy was the way in which Dallas made use of the cliff-hanger ending. With the "Who shot J.R.?" season-end cliff-hanger (the first ever in prime time), fans were left to speculate all summer over the fate of the man they loved to hate and ponder the question of which one of his many enemies might have pulled the trigger. The speculation grew to become an international cause celebre, with the first show of the 1981 season generating Nielsen ratings comparable to M*A*S*H's season finale, and pointing to the overlooked profitability of high-stakes serial narratives in prime time. Hagman's J.R. was influential in making greed and self-interest seem seductive, and the characterization inspired countless other portrayals (both male and female) on spin-off shows such as Knots Landing, and other night-time soap operas such as Melrose Place. 

Since the end of the Dallas series, Hagman has reprised the role of J.R. in a couple of made-for-television movies about the further adventures of the Ewing clan, and he has acted in several other film and television projects. He has also been active in anti-smoking campaigns, producing a videotape entitled Larry Hagman’s Stop Smoking for Life, whose proceeds went to the American Cancer Society. In 1995 the actor was diagnosed with a liver tumor and later underwent a successful liver transplant. In 2001 he published a memoir, Hello Darlin’.