As far as understand things, Time and Space are integral parts of the universe, and both were created at the big bang, and the universe contains all that there is. So according to some definitions, there is nothing outside the universe.
But physicists have never let things like mere ‘words’ or ‘definitions’ stand in the way of their ideas. Some think there’s a whole bunch of universes, all existing alongside each other. This makes my head hurt to think about it (lots of physics does that), but James’ answer to a previous question might help.