5. Big Show - WrestleMania 19
It's hard to imagine given Big Show's seemingly eternal status as a lumbering midcarder, flopping between heel and face alignments with little warning or reason, he was once a pretty major player in the WWE main event scene. His loss to Undertaker at 'Mania 19 can be seen as the beginning of the slide. The previous year had actually been an incredibly successful one for Big Show, culminating in his capture of the WWE Championship at Survivor Series (which snapped Brock Lesnar's undefeated streak in the process). After losing the belt a month later, he entered into a disastrous feud with Undertaker, eventually losing a plodding handicap match even with the help of A-Train - also known as Albert or Tensai. Since then, Big Show has come nowhere near the heights of his early WWE career - a poorly received pair of World Heavyweight Championship reigns in recent years notwithstanding. He was also made champion of the short-lived ECW revival, another largely unpopular reign.