King Barrel is a character in the Amnesia Custom Story: PewDiePie's Revenge.
As its name implies it is the leader of the barrels. It seems to be three times the size of an average barrel.
PewDie found him in the Throne Room, obviously on the throne.
While a normal dagger could kill a regular barrel, it couldn't kill the king. It could only be killed by a so-called "Master Dagger."
King Barrel is the main antagonist and final boss of "PewDiePie: Legend of The Brofist", where he orders his barrel army to kidnap all of PewDiePie's fans and friends, and then Felix himself, in order to obtain the power of the "Legendary Brofist". He appears in phone conversations with bosses like Generoll Barrel and FalconLover, where he is obscured so that players can't tell what he looks like. He finally appears in the final level, Moon Base, where he jumps down and proceeds to attack the player. In easy mode, he is defeated once they stomp on him 3 times. In Hard difficulty and higher, he enters a second phase where he shoots barrels out of a cannon in his body, and requires more stomps to defeat. Once he's been stomped on enough times, PewDiePie's fans will be released, and combine into a ball, forming the Legendary Brofist. King Barrel questions how PewDiePie managed to do it, believing he should have the power because he had the fans, but Pewds explains that the Legendary Brofist isn't obtained by force, because it's in one's heart, which King Barrel doesn't have, due to being a barrel, and therefore empty inside. Using the Legendary Brofist, PewDiePie destroys King Barrel, saving his fans and the world once and for all. After the credits, the barrels can be seen carrying the remains of their king.