#2 CM Punk (Left WWE in 2014)
Only a few Superstars in the history of WWE could claim to have left such a lasting impact on the business as CM Punk did. A two-time Money in the Bank winner, one of the longest-reigning WWE Champions in the modern era, and various other accolades made CM Punk untouchable.
Therefore, the news of his sudden departure came as a shock to the entire WWE Universe. Little did anyone know that after an outstanding performance in the Royal Rumble match at the namesake pay-per-view in 2014, CM Punk would never step foot inside a WWE ring again.
During an appearance on Colt Cabana's podcast, CM Punk revealed the reasons behind his departure. It's interesting to note that the straight-edge superstar had no interest in squaring off against Triple H at WrestleMania 30, which was the direction the company was heading into.
Nearly 7 years have passed since CM Punk walked out of WWE and to this day, fans are hopeful that the six-time World Champion will return for one final run to end his career on a satisfying note.