4: Edge
Joining the WWF in 1998, Edge truly had a Hall of Fame-worthy career.
A grand-slam champion, the Rated-R Superstar is also one of just two men to win the Royal Rumble, Money in the Bank, and King of the Ring.
But though Edge retired in 2011, it was an injury from much earlier that would lead to this decision.
Competing against Eddie Guerrero in 2002, Edge has said it was a stiff uppercut onto a ladder that damaged his neck, and despite fighting through the pain, he would go under the knife in February 2003.
Returning 14 months later, the Rated-R Superstar has said he knew he was on borrowed time, and further damaged his neck in 2009.
After a botched spear in 2011, Edge was diagnosed with cervical spinal stenosis and hung up his boots.