The concept of a hidden world within our own is also somewhat common. The night circus is like a secret world that only a few are aware of. Similar to how in some other fantasy novels there are hidden realms or magical societies coexisting with the normal world. But what makes 'The Night Circus' different is how it presents this hidden world with such an alluring and magical aesthetic, with the tents and the various performances.
One common theme could be the idea of destiny. In 'The Night Circus', Celia and Marco seem to be fated to be part of the circus and their fates are intertwined. This is a theme seen in many other fantasy novels where characters are on a pre - ordained path.
Another possible common theme is the power of love. In the story, the relationship between Celia and Marco evolves and has an impact on the circus itself. Love often plays a significant role in fantasy novels, either as a driving force or as a source of conflict. However, 'The Night Circus' also has its own unique take on this theme as it is blended with the magic and mystery of the circus environment.