#2 Heidenreich
The big man was seen as the next big thing in WWE, and he was even given an opportunity to join the Road Warriors tag team in an effort to get him over. It didn't work, so WWE doubled down on offensive content and decided to make him a rapist as well. This also didn't work and Heidenreich was released. He retired from wrestling in 2009 but many other retired wrestlers have made comebacks to the company (Goldberg and HBK, for example.)
Why the WWE doesn't need him back: Heidenreich was a dud in the ring and on the mike. He brought very little interest to his character and ultimately failed to get the fans emotionally involved. There's also that controversy surrounding his 'assault' of Michael Cole, which is a black eye WWE would like to avoid drawing attention toward.