Koloff, real name Oreal Perras, was billed as coming from the Ukraine but was really a Canadian.
His biggest moment came in the early 1970s when he defeated Bruno Sammartino in Madison Square Garden to become WWWF Champion.
As I'm sure you've read here or elsewhere, Sammartino was a huge deal in that market. His run as champion had started in 1963, so Koloff's victory in 1971 was major.
Koloff's reign didn't last long. He dropped the title to Pedro Morales, another popular among the New York crowd, a month afterwards.
He passed away after a lengthy battle with liver cancer.