The International Wrestling Grand Prix (IWGP) Heavyweight Championship is the top professional wrestling title in Japanese promotion New Japan Pro Wrestling (NJPW). It was created in 1987 with NJPW founder Antonio Inoki defeating Masa Saito in the finals of the annual IWGP tournament. Throughout the history of the championship, several wrestlers have been forced to relinquish the title due to an inability to participate in title defenses. When a wrestler has been injured or unable to compete for other reasons, tournaments have been held to determine the new champion.