No Mercy (2008) was a professional wrestling pay-per-view event produced by World Wrestling Entertainment (WWE), which took place on October 5, 2008, at the Rose Garden in Portland, Oregon. It was the eleventh No Mercy event and starred wrestlers from the Raw, SmackDown, and ECW brands. It is one of only two WWE pay-per-view events to be held in the state of Oregon, the other being Unforgiven 2004.

Eight professional wrestling matches were scheduled on the event's card, which featured a supercard, a scheduling of more than one main event. The first featured wrestlers from the Raw brand, in which defending World Heavyweight Champion Chris Jericho defeated Shawn Michaels in a ladder match. The other main event featured wrestlers from the SmackDown! brand, in which defending WWE Champion Triple H defeated challenger Jeff Hardy in a standard wrestling match. Three featured bouts were scheduled on the undercard. In a standard wrestling match between wrestlers from the Raw brand, Batista defeated John "Bradshaw" Layfield to become the number one contender for the World Heavyweight Championship. The second was a standard match between wrestlers from the SmackDown! brand in which the Big Show defeated The Undertaker. The third was the predominant match from the ECW brand, a standard match for the ECW Championship, in which the champion Matt Hardy defeated Mark Henry.