#4 Randy Orton, Schizophrenia
When Randy Orton made his debut, he was the cocky, handsome third-generation wrestler with a top-tier pedigree and the attitude to match. He blossomed into the "Legend Killer,' and earned the enmity of the fans.
Over time, Orton flipped from the heel/face roles repeatedly, and slowly his cocky swagger was replaced with an almost demonic need to inflict pain and punishment on his foes -- or their wives, as seen in this clip:
Corey Graves deleted his Tweet! More details HERE.
Clearly, Randy was no longer the "Legend Killer." Now, according to his theme music, he was "hearing voices," voices which compelled him to greater bouts of violence. This sounds a lot like Schizophrenia, a condition in which patients report different people speaking to them inside their head, among other symptoms.
Treatment:
Currently, Schizophrenia is uncurable. It can be managed, however, with the right regimen of psychoactive drugs. Unfortunately, the side effects of these medications can sometimes be as debilitating as the disease itself, meaning a pro athlete like Randy would likely not be willing to take them.