Antonio Inoki won the first IWGP Heavyweight Championship tournament in New Japan Pro-Wrestling in 1987.
The original IWGP concept was created to determine an international wrestling champion through tournaments and championship contests. New Japan Pro-Wrestling held the first major IWGP tournament in 1987, and Antonio Inoki defeated Masa Saito in the final to become the inaugural champion.
Inoki was already one of Japan’s most influential wrestlers and had founded New Japan Pro-Wrestling in 1972. His victory connected the new championship concept with the promotion’s founder and leading star.
The title’s lineage later continued through several name and championship-status changes. The modern IWGP Heavyweight Championship was established as a regular defended title in 1987, while the IWGP United States and IWGP World Heavyweight Championships became separate parts of New Japan’s title system decades later.