Quaznock
A realm that includes not just all universes, both real and fictional, but also includes anything described by anyone in the past, present, or future. For instance, if someone declares themselves to the the ruler of the Quaznock, another person cannot claim to rule an infinite number of quaznocks, because the Quaznock already includes an infinite number of quaznocks. The Quaznock includes, just to name a few things, the Multiverse; every possible version of every possible reality; every impossible version of every impossible reality; the entire universe; an infinite number of universes; an infinite number of infinite universes; an infinite number of infinite universes multiplied by infinity; everything you can possibly imagine in the past, present, or future; everything you can't possibly imagine; and anything that has not been named in this definition.
I am Absolute Supreme Ruler of the Quaznock. I would say there is nothing outside my rule, except 'nothing' is another thing I rule over.