6. Chess Boxing
Chess players are not traditionally good at boxing, and most boxers don't seem like they would be any good at chess. This majestic mutual exclusivity makes for a very interesting hybrid—chess boxing.
The ultimate test of brains and brawn, this sport was invented by a performance artist in 2003, and unsurprisingly is big in Russia. You can win via checkmate or knockout. The rules alternate chess and boxing, but since the rounds are so short you have to be good at speed chess, not necessarily classical chess.