#4. Former WWE NXT Champion Aleister Black
Aleister Black has already proven he's capable of winning titles and achieving success in WWE as not only is he a former NXT Champion, but before he ever won the title he had a prolonged undefeated streak.
Black also has the Black Mass finishing move, which much like the RKO, enables him to believably beat any opponent, even those with a massive size advantage, in just a fraction of a second.
But, for whatever reason, those two things didn't translate over to RAW or SmackDown very well and after only just returning from time away from television with a new character, Black was released.
Rumors suggest that many within WWE were surprised by Black's release and some have actively campaigned for him to return. Although the latest development indicates he's more likely to sign for AEW than return to the company that released him.
Everything's there for Black to be a major contender in WWE, so should he return all WWE would have to do is book him like they did when he first arrived in NXT. If they manage to do that it's almost guaranteed he'll win a world championship!