When I was much younger I would have either answered JR and Bobby or JR and Pam. Now my answer is different. Now I'd say JR and Cliff were the two most essential characters to Dallas. JR easily tops the list of most essential Dallas characters. It's no coincidence that he was the most talked about Dallas character both in the show and in real life and that he was the most essential character to the show. In TV series in the style of Dallas, actors are paid in relation to their worth to the show. Larry Hagman's salary showed how his importance to Dallas compared to the salaries of other actors on the show. If I remember correctly, when Dallas's most famous cliffhanger aired - the beginning of the "Who Shot J.R." mania - Hagman had the highest salary on the show and the next two were Duffy and Principal although I don't know which was paid more or if they were paid equally. Despite already commanding the highest salary on the show, Hagman renegotiated with the network and his salary was drastically increased, commensurate to the amount of publicity "Who Shot J.R." had created. J.R. had become the most talked about character on all of television and Larry Hagman had become the highest paid actor on TV. Bobby was considered important enough that the people running the series were willing to say that everything we'd seen happen for a whole season didn't happen because it was just a bad dream. That's a questionable decision but it's a huge compliment! It showed just how important they considered Bobby. They thought they needed him back no matter what damage the show's credibility took in the process. I don't think you can ever justify killing the show's credibility for the sake of any one character. Still he was extremely important to the series, primarily for two reasons. One reason was he was half of what is sometimes called Dallas's "Cain and Abel" story. Bobby and JR loved each other no matter what happened, no matter what the other did. It was unconditional love - what you hope to have between family members. They were extremely competitive with each other though, and they had very different mindsets. The two of them viewed the world in very different ways. The two of them brought out the best in each other. Jock knew this when he wrote the codicil to his will in which he stated that the purpose of the contest had been to teach Bobby and JR to respect each other's abilities as businessmen and to have them both come to realize that they were far better off working together instead of working against each other. That competitiveness between JR and Bobby and the various attributes each brought with him to Ewing Oil was a huge part of what Dallas was about. Bobby found himself in the role of being the moral compass for Ewing Oil. After Jock died, it was up to Bobby to try to reign JR's impulsivity in and to temper some of JR's more underhanded tactics with ethical standards. Bobby wanted Ewing Oil to stand for more than just making money any way possible. So without Bobby, JR would be free to take Ewing Oil in any direction he wanted. If Bobby had been like Gary and shown no interest or aptitude for business, Jock would have left Ewing Oil entirely to JR, who would have been free to run it any way he saw fit. We would have missed out on all the great stories provided by the conflict between the ways JR and Bobby wanted Ewing Oil run as well as their contest for control of Ewing Oil. That was huge. As far as I'm concerned the contest for control of Ewing Oil was the best, most exciting storyline in Dallas history. Pam was extremely important to Dallas. She was one half of Dallas's "Romeo and Juliet" love story. It was inarguably the greatest love story Dallas had. Like the characters Romeo and Juliet, Bobby and Pam came from families who were feuding with each other. There was bad blood between the Barnes and the Ewing families and Pam literally brought that closer to home than anyone else would have thought possible - brought it right into Southfork. To Pam's credit, she hated the feud and was almost always trying to put an end to it. She played the role of the peacemaker in the Barnes-Ewing feud. Nobody wanted that feud ended more than Pam. Their marriage was so significant that it was the very first thing the series focused on. The first image we saw was Bobby and Pam headed toward Southfork to bring the "good news" to the Ewings that they'd gotten married. Cliff wasn't likable in the way Bobby and Pam were. Bobby and Pam were two of the nicest characters in Dallas, maybe THE two nice people in Dallas. Cliff wasn't a peacemaker like Pam; he was the opposite. His biggest role was in making sure the Barnes-Ewing feud continued. It was a tremendous feud - maybe the greatest feud in TV history. It was the source of tremendous storylines year after year. Nothing seemed capable of deterring Cliff from trying to win this feud. Even though JR got the upper hand in almost every situation where Cliff and he clashed, Cliff just would not go away. Cliff just wouldn't quit. He allowed himself to be consumed with the desire for revenge to the point where you could say he had become obsessed with the Ewings but especially JR - despite Jock being the man who had supposedly stolen Digger's fortune, ruined Digger's life in the process and the man who Digger once tried to shoot. Cliff's obsession with perpetuating the Barnes-Ewing feud, despite Pam begging him to please stop feuding with the Ewings, his bitterness, and his ability to absorb punishment while continuing to instigate situation after situation which forced the Ewings to fight back or be put out of business was what I consider to be why he and JR were the two most essential characters to Dallas.