The original version of IWGP Heavyweight Championship (IWGPヘビー級王座, IWGP hebī-kyū ōza) was a professional wrestling world heavyweight championship owned by the New Japan Pro-Wrestling (NJPW) professional wrestling promotion.

"IWGP" is the initialism of NJPW's governing body, the International Wrestling Grand Prix.

Subsequently, the championship was defended annually against the winner of the IWGP League of the year.

[2] The inaugural champion was determined in the 1983 edition of the IWGP League, a 10-man round-robin tournament.

Inoki successfully defended it in 1985 against Andrè the Giant (IWGP League winner of 1985) and Hulk Hogan.