Koloff, nicknamed "The Russian Bear," was a rival of star wrestler Bruno Sammartino, and the two had many memorable moments in the ring.
Koloff suffered from liver disease, according to his daughter, Rachel Marley. She started a GoFundMe page to raise funds for medical expenses and encourage fans to send cards and prayers.
Hulk Hogan posted his condolences on Twitter, saying that it had been a rough week for the wrestling community. George "The Animal" Steele and Chavo Guerrero Sr. also died recently.