Holy cliffhanger! On March 21, 1980, Dallas fans were stunned as Larry Hagman's villainous J.R. Ewing was gunned down on the CBS drama's Season 3 finale. After eight agonizing months, and a masterful marketing campaign that turned "Who Shot J.R.?" into a worldwide phenomenon, the shooter's identity was finally revealed in Season 4's fourth episode, "Who Done It," which aired Nov. 21, 1980. More than 83 million people tuned in—a whopping 76 share, and an estimated 350 million worldwide—making it the U.S.'s second most-watched non-sports program of all time, after the MASH finale in 1983.