Boy has there been a lot.
I'll stick to about three or four.
I guess I'll start with Ricky Steamboat. He deserved so much better in the WWF when he was there. He could have been a World Champion. The one title he did win was a very short reign. He was lucky he was treated like a god in Jim Crockett Promotions and WCW.
Another one is a guy who's still with the company, The Big Show. He should have been brought in as an unstoppable force but within a year was after losing to most of the roster. It was hard to take the guy serious. He's a four-time World Champion in the WWE but all the reigns have been poor and he's changed from face to heel so much it's not even funny.
I am one that thought Mr. Kennedy was becoming a bit of a liability but I can't deny the guys talent. He could have been a major player. Maybe he should have been a World Champion earlier. I wouldn't have minded him having a rookie year like Angle and Lesnar and winning it in 2006. Now he's wasting away in TNA and even though he's been a two-time World Champion, he's has been shoved down the fans throat so much that it's become unbearable.
The last one I'd say is the most recent, John Morrison. Seriously, the WWE had a superstar standing right in front of them and they just let him pass by. He was great in the ring and was great on the mic as a cocky heel. What wrestler doesn't have an ego backstage, it seems mandatory, yet he got punished for it. I'm sure he'll return later this year but will he have the same impact.
Those are some I can think of, who do you think.