John Wisniski, Jr. is an American professional wrestler, better known as Greg "The Hammer" Valentine. He is the son of wrestler Johnny Valentine. In the course of his career, which has spanned over four decades, Valentine has held more than 40 championships, including the NWA United States Heavyweight Championship and the WWE Intercontinental Championship. An alumnus of WWE and World Championship Wrestling, he was inducted to the WWE Hall of Fame in 2004.

• WWE WrestleMania IV (1988)