How many characters do operas normally have in them?

There is no set number of characters in an opera. The number of characters can range from a single protagonist to a large cast of dozens. The size of the cast depends on the story being told and the composer's preferences. Some of the most famous operas, such as Mozart's "The Magic Flute," have relatively small casts, while others, such as Wagner's "The Ring of the Nibelung," have very large casts.