12. Pat LaFontaine (1998)
Concussions have received a lot of media attention in recent years. They occur in many sports from football to hockey. Nowadays, leagues are more responsible when it comes to dealing with player trauma. This is because they are afraid of the legal ramifications. However, it wasn’t always like this. LaFontaine played an entire season against doctor’s orders in 1998.

A Penguins enforcer left LaFontaine with a brutal concussion in 1997. The Buffalo Sabres refused to allow him to continue playing for the franchise because of the career and life-threatening risk to his health. However, the New York Rangers didn’t have any qualms about this and duly signed him up. He then smashed into a teammate and suffered another savage concussion. Finally, he retired from hockey forever.