Larry Hagman, who created one of American television’s most supreme villains in the conniving, amoral oilman J.R. Ewing of Dallas, died on Friday, according to a co-star. He was 81.  

Hagman died at a Dallas hospital of complications from his battle with throat cancer, the Dallas Morning News reported, quoting a statement from his family. He had suffered from liver cancer and cirrhosis of the liver in the 1990s after decades of drinking.

Linda Gray, who played J.R.’s long-suffering wife, Sue Ellen, was with Hagman in Dallas when he died, the actress’ spokesman, Jeffrey Lane, said in an email.

Hagman’s mother was stage and movie star Mary Martin and he became a star himself in 1965 on I Dream of Jeannie, a popular television sitcom in which he played Major Anthony Nelson, an astronaut who discovers a beautiful genie in a bottle.

Dallas, which made its premiere on the CBS network in 1978, made Hagman a superstar. The show quickly became one of the network’s top-rated programs, built an international following and inspired a spin-off, imitators and a revival in 2012.

Dallas was the night-time soap-opera story of a Texas family, fabulously wealthy from oil and cattle, and its plot brimmed with back-stabbing, double-dealing, family feuds, violence, adultery and other bad behavior.

In the middle of it all stood Hagman’s black-hearted J.R. Ewing — grinning wickedly in a broad cowboy hat and boots, plotting how to cheat his business competitors and cheat on his wife. He was the villain TV viewers loved to despise during the show’s 356-episode run from 1978 to 1991.

In his autobiography, Hello Darlin’: Tall (and Absolutely True) Tales About My Life, Hagman wrote that J.R. originally was not to be the focus of Dallas but that changed when he began ad-libbing on the set to make his character more outrageous and compelling.