#1 Ethan Carter III / EC3
The man today known as EC3 was a part of WWE TV since 2010 when he appeared on season 4 of WWE NXT as Derrick Bateman. He would then stay in NXT until 2013, before being released from his contract.
He joined TNA and adopted the character of Ethan Carter III, the spoilt nephew of then-President Dixie Carter. He would have great feuds and matches against legends like Sting, Kurt Angle, Bobby Lashley and Matt Hardy.
Having been a heel since his debut, a double turn in a match against Hardy saw EC3 become the most popular babyface in the company, proving he can work well in any persona. He left Impact Wrestling in 2018 to re-sign with WWE weeks later.
After a short stint in NXT, EC3 was rushed to the main roster. He traded wins with Dean Ambrose and since then has only been used in comedy segments for the WWE 24x7 Championship, which he has held on four occasions.
It is shocking how some of the most popular and over characters in Impact just failed to make it big in WWE.