This is a difficult question to answer, but going by the definition of "universe" as the totality of existence, I suppose a Creator, who exists and therefore must be a part of existence, should be included. The problem being, however, is that this would make the universe circular. In order to find the origin of existence, you must look into the origin of the Creator. In order to find the origin of the Creator, you must look into the origin of existence. In the end, looking for a source brings you nowhere.