God damn there are so many I don't even know where to start.
Taz
One of the greatest wrestling technicians in the history of the biz, and the guy gets completely buried within his first six monthes in the company. I'm sorry but when you have a guy like this getting his ass kicked by Jim Ross, theres a problem. The only times they ever really utilized him was in his debut match(which was done to perfection), his ECWvs.WWF Title match with HHH, and some of his hardcore matches. The man should've been a WWE champ, theres not a doubt in my mind as he is one of the best of all time. Criminal.
Jerry Lynn
Yet another one of the greatest in ring performers of all time, if you've only seen his three or four odd matches on old episodes of Heat, you should be ashamed of yourself. Lynn's series of matches with RVD are some of the greatest wrestling matches I have personally ever seen. They didn't even give Lynn a chance, which is what really pissed me off. Like people said before, they can make time for Shawn fucking Stasiak(Meat!) but not Jerry Lynn? Thank god he moved over to TNA where he's been able to show us he still has boatloads of talent.
Kid Kash
Although he was a Cruiserweight champ in his time at WWE, I don't remember ever seeing him wrestle on RAW or Smackdown. He just wasn't there, he probably didn't defend the title for like five or six months if I remember correctly. This guy easily could of helped put some respect into the CW division, he's one of the most talented lucha style performers in a while IMO.
Raven
It's been said too about Raven but I'll have to say it myself as well. This guy is just a genius, Scott Levy is a freaking genius. His promos in ECW will always be the be all and end all of how to be a good heel. He may not have been the most talented guy in the ring, but he sure as hell made up for it in heart and charisma. His intelligence of wrestling is huge too, which led him to wanting to be on the WWE's creative team, thus leading to him being fired and blacklisted. God damn shame the politics backstage forced out the possibility of feuds and angles being written by RAVEN.
Stevie Richards
Granted, he was never really main event material. But Stevie was a breed of his own, guys like him and Al Snow add credibility whenever they're given the chance to shine, something Richards never got when he was sacked into the Right to Censor gimmick, one that instantly made the fans hate him forever. Not even just heel heat either, X-Pac heat. What else do you expect when you have a guy trying to stop you from seeing boobs? Check out his work with Raven in ECW to get a feel of his in ring style.
2 Cold Scorpio
I guess this would go under ECW and WCW. But the guy was just completely abused. He made sporadic appearances after his horrifying Flash Funk gimmick pissed everyone within a one mile radius off, and then was put into the JOB squad for christ sake. From there he just disappeared. This man is one of the most technically sound guys out there who's also amazing in lucha style---his 450 Splash is the best in the business.
Super Crazy
Not many of the modern WWE fans have ever seen Super Crazy truly shine in his style. For some reason or another the WWE has decided to keep Super Crazy away from anything that even resembles a cruiserweight or lucha libre match, which is what he excels in. His international three ways back in ECW with guys like Little Guido and Tajiri were simply stunning. Not to mention he is one of the most agile performers I've ever seen, I have never once seen him not land on his feet after doing an Asai moonsault from the apron or some other crazy height.
Yoshihiro Tajiri
Same thing with Super Crazy pretty much. Although he did have a few solid matches in his time at WWE, he was mostly just buried in the undercard with wrestlers who's styles he did not mesh with well at all. If they had put him into a cruiserweight scene he would've been amazing and I guarantee we would've seen some great matches.
Mike Awesome
Classic big man who has always impressed me. Of course if you don't know, check out any match involving this man and Masato Tanaka, and I guarantee you will be amazed. Crazy son of a bitch with one of the most vicious power bombs to go along with a beautiful frog splash and his mid rope planchas. Easily could've added stability to any midcard scene.
Lance Storm
Again, man was buried instantly, especially with his gimmick. Everyone fucking hated him when he showed up in the WWE. This man is another amazing in ring technician, one of the best of all time, who could probably go hold for hold with Dean Malenko. Imagine the classics if they had let guys like Storm, Lynn, Tajiri and so forth wrestle?
All of the ECW Originals[Sabu, Sandman, Tommy Dreamer...well not RVD of course]
What is the point of having three of the best hardcore wrestlers out there never wrestle in hardcore matches? That's just plain stupid business.
That's all for now.
Now if we could just get into some of the WCW wrestlers they buried...*cough*DDP*cough*