Sullivan had been an amateur wrestler in the Boston area, and was not trained professionally. His first professional match was in Montreal, beating Fernand Frechette.

Known as the heel "Boston Battler", Sullivan's "The Prince of Darkness" gimmick started during this time. In CWF he became associated with "Maniac" Mark Lewin (Purple Haze), Mike Davis, Bob Roop, The Lock and Luna Vachon and others as the Army of Darkness. His biggest rivals during this time included Dusty Rhodes, Barry Windham, and his former partner Mike Graham. Sullivan split his time with International Championship Wrestling and brought "The Prince of Darkness" gimmick there, along with Lewin and Roop. He had the Fallen Angel as his valet, who later became known as Woman. Sullivan was the top heel in ICW when the company first went national and had noted feuds with Austin Idol, Superstar Billy Graham, Bruiser Brody, Joe Savoldi and Blackjack Mulligan.

He is a Wrestling Legend and Hall of Famer (Wrestling Hall NOT WWE HoF)