#2 The Nexus

When the Nexus debuted on ‘Viewer’s Choice’ episode of Raw, they definitely did leave their mark. They attacked Cena, Punk, Jerry Lawler, ripped apart the ring and also beat down the WWE personnel around the ring. Over the weeks, they increasingly starting giving the vibes of nWo as they attacked whenever their demands were not met.
That all changed when they lost at Summerslam to a team of John Cena, Jericho, Edge, R-Truth, John Morrison and a returning Bryan. They lost a lot of momentum and credibility and after a forgettable Tag Team Championship run, they soon disappeared and split into two groups: The New Nexus and The Corre, neither of which achieved anything significant in their WWE run.
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It is worth noting that nobody from the original Nexus is in the company right now except Heath Slater, who is a jobber and David Otunga, who only does commentary.
Had WWE treated this group a letter better and booked them along the lines that WCW booked nWo, they could have left a mark and could perhaps have succeeded in their singles career.