The Big Show entered the year 2000 as the WWF Champion, in my opinion the worst WWF champ ever. My best guess is that Paul Wight had a clause in his contract guaranteeing him the title, since Vince desperately wanted to start luring away WCW talent. This was fine since HHH was involved in a more interesting storyline with the whole McMahon/Helmsley thing, Rock and Mankind were fighting as a tag team and Austin was hurt. So the Show was snuck in as champ, but with a new year, a new champ was needed.
Triple H started the millenium by winning back his title, ending the reign of The Big Show, on January 3rd's edition of Raw is War, setting up the match while he was in charge of the WWF. Once Triple H won the title, its air of legitmacy was returned. Triple H would hold the title going into Wrestlemania, headlining that event for the first time in his career. He would leave Wrestlemania as champion as well, defeating the Rock, Mick Foley and the Big Show with the assistance of his father-in-law, Vince McMahon.
In one of the most surprising Raw matches ever, Jericho was to fight Triple H as punishment for the disparaging remarks that Y2J had made about The Game's wife, Stephanie. Jericho managed to convince HHH to put his title on the line, brought out the APA to protect him from DX, and with the help of a quick count from referee Earl Hebner (whom HHH had been picking on), beat Helmsley to win the WWF title! However, Triple H used his influence to get Hepner to reverse his decision so that Jericho never actually won, thus never actually being WWF Champ.
With Shane McMahon as guest referee, The Rock dominated Triple H for the entire match at Backlash. Of course, with Shane-o Mack in stripes it wouldn't matter. Eventually, after McMahon was Rock Bottomed through the Spanish announce table (always there when you need it), and the stooges were defeated, Stone Cold Steve Austin made his long awaited return to clobber Triple H and help the Rock become 4 time WWF Champion.
Triple H would regain his WWF Title on May 21st, becoming a 4 time champion, during a 60 minute Iron Man Match at Judgement Day. With the Heartbreak Kid Shawn Michaels serving as guest referee, the Rock and Triple H had tied the match at 5 wins a piece. Then, HBK was knocked out accidently by the Rock (those officials are pretty delicate aren't they?). The rest of DX decided to come to ringside to take advantage of the situation only to be greeted by the sounds of Kid Rock, and the return of the Undertaker from a long layoff. Taker fought his way through DX, and tombstoned Triple H, just as the match was ending, just in time for HBK to come to and give Helmsley a DQ win. Time was up, HHH held a 6-5 edge and won the title.
At the King of the Ring, Linda McMahon decided to challenge her husband's authority by scheduling the main event as Champion Triple H, teamed with Shane and Vince McMahon against the team of the Rock, the Undertaker and Kane with any of the three faces winning Helmsley's title if they score a pin on any of the former three. Triple H would keep his title if any on his team wins. You follow? After much jockeying back and forth, the Rock defeated Vince to become 5 time WWF Champion. Rocky's reign included a feud with Chris Benoit that saw Benoit be declared winner twice, only to have both decisions immediately overturned.
Kurt Angle completes his miracle year on October 22nd at the Survivor Series, winning the WWF Title with Stephanie McMahon-Helmsley at ringside as his "business partner" when the Undertaker returns to give Angle "the Last Ride", thus disqualifying the Rock. Commissioner Mick Foley, fearing what the Rock might do, added the special stipulation that the title could change hands on a DQ. Angle now heads into the year 2001 as champ after successful defences against the Undertaker at No Mercy and the 6-man Hell in the Cell Match at Armageddon.