Rey Mysterio
He may have been really over win the fans ever since he came to the company, but I really never thought I would see the day that Vince would put the World Title on a man who is the size of a child. It must have been a huge decision for him, risking making a mockery of the title by putting it on a 5'3 guy, no matter how popular and entertaining he is.
Mankind
He never looked like a star, he didn't even look like an athlete but Mick Foley achieved what noone ever thought he would when he became the WWF Champion in one of the all-time greatest wrestling feel-good moments. He deserved it, no question but who would have believed that the title would be won by someone who just did not look like they had it in him. It was a great moment for me, I was so happy to see Foley on top but it certainly shocked me.
Sheamus
A rookie beating the biggest star in the business in his first crack at the title after only debuting on the show a few weeks earlier? WOW. That took me totally by surprise and it was another huge gamble by the WWE, but this one has eventually paid off with Sheamus recognised as a genuine superstar now.
Chris Jericho
Everyone could see that he was going to be a champion one day, but when the WCW and WWF titles were unified, which was a HUGE deal, noone really thought that Jericho would be chosen as the 1st Undisputed WWE Champion ahead of the 2 biggest names in the business in Stone Cold and The Rock. Not only was Y2J chosen, but he beat both of them in one night, showing the faith that WWE had in him.
JBL
After spending all of his career as a tag team or lower card wrestler, Bradshaw changed his gimmick and almost immediately was put in the main event heel position on SmackDown, where he won the title quickly. This really shocked me, I never dreamed in a million years that Bradshaw would ever hold the WWE title, and I am betting almost no other fans thought that either. However, he kept the belt for a year, and ended up a well-regarded main eventer. So another good decision from the WWE.
Vince McMahon
Come on, who really thought he would ever wrestle a match, let alone win the title??? Simply for storyline purposes it worked, but it did make a mockery of the belt.