Koichi Watanabe, better known as Koichi Pettas or simply KOICHI, was a Japanese heavyweight kickboxer competing in K-1, It's Showtime and GLORY.

Nicholas Pettas is a Greek-Danish karateka, former heavyweight kickboxer and actor, who fought out of Team Spirit AE in Tokyo, Japan. Pettas mainly competed in the promotion K-1 between 1998 and 2007, and was the winner of the K-1 Japan Grand Prix 2001.