One of the older and more beloved 4chan image memes, Longcat is a cat who is quite long. Indeed his true length cannot be measured by mortal means as it passes through all dimensions of existence.
Within the Catnarok mythology (see Ceiling Cat) it is believed that one day Longcat will engage in a mighty final battle with his anti-self, Tacgnol (Protip: Longcat spelled backwards).
Sometimes this event is interpreted as the Apocalypse, while others take a more Taoist approach and consider it to be an eternal battle.
Below, an interpretation of Tacgnol and Longcat's epic battle.