9. Chris Spielman
After missing a season and a half to recover from a serious neck injury and to tend to cancer-stricken wife, everyone was pulling for Chris to come back in the 1999 season. But then his neck was reinjured during the preseason, and he never played again.
10. Bubba Smith
When this Colts running back rushed toward the sideline to go out of bounds on a first down, he crashed into a metal pole used as the first down marker. The resulting injury led to some changes in how first downs are marked.