There's no way anyone can dispute the significance of either Sting or Bully Ray in TNA. Both guys have had tremendous careers in TNA and both deserve plenty of accolades. However, there's no way I could justify considering either of them TNA originals. Neither was around in the earliest days of the company, and both guys achieved considerably more success in their days preceding TNA than they did in their days spent there. They were already established veterans before ever entering the six sided ring (then four, now six again). Charismatic? Undoubtedly. Skilled superstars? Undeniably. But TNA originals? Not according to my definition.
I think the dubious honor goes to Jeff Jarrett. You can't get any more original than the guy who started the company, and who spent years there until being cast out a couple of years ago. And I would consider him a pretty charismatic dude. Is he as skilled in the ring as guys like Bully or Sting, is he as talented a superstar, obviously not, but that wasn't the question here, the question here was concerning charisma. When Jarrett was a face, he was quite successful at getting the fans behind him. When he was a heel (more frequent), he was quite capable of eliciting quite a negative response form the crowd. At his heelish best, no one got booed any more vehemently that Jeff Jarrett. And that's charisma, a guy able to get the fans in the palm of his hand, sometimes positively, sometimes negatively, but eliciting a strong response either way.
Sure, he achieved success elsewhere before his TNA tenure, in both WWF and WCW and possibly elsewhere too. But he was never really a main event player there. He was a strong mid carder in these other organizations, not really a top guy. My vote for most charismatic TNA original, Jeff Jarrett.
Honorable mention to Robert Roode, although I'm not sure how far back his time with TNA extends. He's been there since I've been watching, but I'm not sure if he is technically an original either. And to those who said AJ Styles, really? Dude is a tremendous talent, very skilled in the ring, better on the mic than he gets credit for in my opinion, but charismatic is not an adjective I would use to describe him, in fact, he's more of a charisma vacuum than anything.