It was the daddy of all cliffhangers: Who Shot J.R?

On March 21, 1980, 'Dallas' viewers gasped as an unknown assailant shot J.R. Ewing (Larry Hagman), the ultra-manipulative, double-dealing womanizer we loved to hate. The Texas oil baron had so many enemies, anybody could have pulled the trigger. Was it his bitter alcoholic wife Sue Ellen? His upright but resentful brother Bobby? His arch-enemy Cliff Barnes, who blamed him for stealing his daddy's oil business? Or any number of other relatives, business associates, mistresses (or their angry husbands), who had ample motive for revenge?

It was an unprecedented pop culture moment with "Who Shot J.R.?" T-shirts and Vegas laying odds about who the culprit would be. Ninety million people tuned in the next fall to find out that the shooter was Kristin, J.R.s sister-in-law whom he'd also been sleeping with.

The show never again reached such ratings heights, but the cliffhanger craze was born. Over the next 12 seasons, we were treated to crashes, fires and all kinds of bite-your-nails finales that left nearly every character's life on the line at some point. In honor of the 30th anniversary of that fateful shot, we count down 'Dallas's top 10 most memorable moments.