Here are some options, depending on the context:
* Cast: Often used for a group of characters in a play, movie, or book.
* Ensemble: Similar to "cast," but can also refer to a group of musicians or performers.
* Gallery: This term evokes a sense of a collection or display of characters.
* Roster: More formal and often used for a list of characters in a story or game.
* Panoply: Implies a wide and varied collection of characters.
* Spectrum: Used for a diverse group of characters with different qualities or perspectives.
You can also use descriptive phrases like "a tapestry of characters", "a host of personalities", or "a constellation of characters" to convey the specific nature of the group.
Ultimately, the best collective noun depends on the specific context and the nuance you want to convey.