International Roller Derby League
Years of Existence: 1949-1973
Before guys were skydiving off of satellite dishes and snowboarding into volcanoes, adrenaline junkies got their jollies through roller derby—the original extreme sport. Hockey players get a lot of credit for being the toughest guys in sports, but playing through level three concussions and chipped teeth just doesn't seem so badass after seeing RollerJam's in-course pit full of live alligators. If introducing polar bears or hungry leopard seals to the ice of NHL games is included in the next collective bargaining agreement, we'll be back on board.