The Giant Cannon is a large cannon that appears in Paper Mario: The Thousand-Year Door.
The Giant Cannon is located in Fahr Outpost where Mario and company wanted to use it to get to The Moon. However, the mayor claimed there were no such cannon until Admiral Bobbery yells at him saying he has seen the cannon himself before. Even so, the mayor refuses to let the heroes use the Giant Cannon until get they permission form Goldbob and General White. Once they do, an army of Bob-ombs load into the Giant Cannon and blast Mario and the others to The Moon.