Top 20 Knockouts In UFC History (Video)

20 years ago this month, UFC 1 took place in Colorado. Just 2,800 people were in attendance and 86,000 watched on pay-per-view, but no one could imagine the type of beast the promotion would go onto to become... and the type of impact it'd have on the sport.

Today, as the UFC celebrates their 20th anniversary this Saturday (Nov. 16) at UFC 167, headlined Georges St-Pierre and #1 contender Johny Hendricks, here's a look back at the top 20 in its history. From Chuck Liddell's knockout of Tito Ortiz at UFC 47 to Chris Weidman's stunning upset KO of Anderson Silva at UFC 162 this past summer, they're all here.