#1 CM Punk
In 2006, a young CM Punk joined the WWE, appearing on its ECW brand, and instantly became a star.
The biggest star to come from the company's third brand, it wouldn't be long until Punk held championship gold, winning the ECW Title the next year.
In 2014 though, after a long career which had seen Punk hold the WWE Championship for an incredible 434 days, Punk walked out, citing issues with how he was being treated.
As one of the company's most popular stars, many fans instantly sided with Punk, making the WWE look bad.
The company looked even worse when the Straight Edge Superstar claimed that Dr. Chris Amann had encouraged him to compete whilst injured.
Though (most) fans have moved on from Punk now, five years later, his leaving definitely made the sports entertainment juggernaut look bad.