The 2005 Armageddon was the sixth Armageddon professional wrestling pay-per-view (PPV) event produced by World Wrestling Entertainment (WWE). It was held exclusively for wrestlers from the promotion's SmackDown! brand division. The event took place on December 18, 2005, at the Dunkin' Donuts Center in Providence, Rhode Island.

The main event was a Hell in a Cell match between Randy Orton and The Undertaker, which Undertaker won by pinfall after performing a Tombstone piledriver. One of the predominant matches on the card was an Interpromotional tag team match between WWE Tag Team Champions Rey Mysterio and World Heavyweight Champion Batista and World Tag Team Champions Big Show and Kane. Big Show and Kane won the match after Kane pinned Mysterio following a chokeslam. Another primary match on the undercard was Booker T versus Chris Benoit in the fourth match of their "Best of 7" series for the vacant WWE United States Championship. Benoit won the match after forcing Booker to submit with the Crippler Crossface, thus earning his first victory in the series.