SCP-666 SCP 121212 because 666 multiplied by twice as evil is 121212
Special containment procedures: He will end the world some day NO MATTER WHAT but you must feed him the souls of dead D-Class every day (he will kill you if you don't give enough) and lock it in a room with a lot of asdkfheiuorhiuwrnwekjfhfiugffgtrtjkjhgcesqauiohgdfiuhweiurooxide.
Description: He is a devil that kills you and changes stuff with his mind powers. He is big and red with scary horns and he spits ieuwrhwuipdfiusic acid that makes you insane if it touches you. He eats souls and kills you if he is hungry but kills the universe when he is full. When you die you go to hell because he is a devil and people in long robes worship him more than Cthulhu. He will end the world no matter what so stop trying.
Sometimes he makes cubes that are universes, but no one cares about that.
Addendum: He makes a universe in a universe that is bigger with everything in the universe in it but more and in another universe that has every little thing in existence in it including existence itself but because 121212 created it he isn't inside it. 121212 is stronger than the strongest thing in the world and even stronger than that if he eats more souls where he becomes omnipotent but is more omnipotenter when he kills you, the reader and turns into you.