If "personas" refers to individuals:
* Nadie: This means "no one" and is the most direct opposite.
* Ningún: This means "no one" or "none" and is used with a noun.
* Nada: This means "nothing" and can be used to refer to the absence of individuals.
If "personas" refers to characters:
* Realidad: This means "reality" and implies the opposite of fictional characters.
* Gente real: This means "real people" and emphasizes the distinction from fictional characters.
* Seres vivos: This means "living beings" and is a more general term for non-fictional entities.
Other possible opposites:
* Cosas: This means "things" and is the opposite in the sense that it refers to objects instead of people.
* Objetos: This means "objects" and has a similar meaning to "cosas."
Ultimately, the best opposite for "personas" depends on the specific situation and what you want to convey.