#4 Bruno Sammartino (1,237 days)

The start of the reign: The legendary Bruno Sammartino enjoyed two lengthy spells with the title. His second lasted a total of 1,237 days, beginning with a victory over Stan Stasiak at, you guessed it, MSG in December 1973.
The end of the reign: As we mentioned earlier, Superstar Billy Graham won the title for the one and only time in his career when he brought a shocking end to Sammartino’s three-and-a-half-year reign at a Baltimore house show in April 1977.
#3 Bob Backlund (1,470 days)
The start of the reign: Antonio Inoki’s six-day reign with the title came to an end in December 1979 when he vacated it after his rematch with Bob Backlund ended in a no contest. Two weeks later, Backlund regained the vacant title when he defeated Bobby Duncum in a Texas Death match.
The end of the reign: After a four-year reign as champion, Backlund lost the title to The Iron Shiek at MSG in December 1983 when his manager, Arnold Skaaland, threw in the towel to stop Shiek from applying any more pressure with his camel clutch submission.