#2 Pedro Morales held the Intercontinental Championship for 425 days
Pedro Morales' Intercontinental Championship reigns were something to behold for his generation. His first reign in 1980 saw him become the first-ever 'Triple Crown' champion in WWE history. In his second reign, he became the second longest Intercontinental Champion in history.
Of course, during this period, Morales was embroiled in a feud with Don Muraco over the Intercontinental Championship. Morales' second reign came when he defeated Don Muraco in November 1981 at Madison Square Garden. It was broadcasted on WWF on MSG Network.
A reign that lasts well over a year is something we don't quite see in modern day professional wrestling. The closest we have gotten to that kind of reign was CM Punk's reign as WWE Champion which lasted 434 days between 2011 and 2013.
In regards to the Intercontinental Championship, the longest reign we've had in the modern era came in 2011, where Cody Rhodes held the championship for 234 days on SmackDown. Following that, it was Shelton Benjamin, 2004, holding the gold for 244 days.