Michael Vick
There was a time when Vick was the most exciting quarterback in the NFL. He changed the sport with his unbelievable rushing but destroyed his legacy. It emerged that he was the leader of a dogfighting ring and he went to jail for 21 months. However, he returned from the depths of Hell after his release (via Bleacher Report).

NFL franchises don’t care what an elite quarterback has done as long as he’s walking free. The Philadelphia Eagles infuriated animal rights activists across the world when they signed the new free agent. Vick insisted that he had learned the error of his ways and regretted his horrible actions. He successfully revived his career despite everything going against him.