Show one model (of a character, for example) from a list.
I recommend putting this script directly onto your character (an active object on the character, like the parent or root).
Press the LOCK button in the inspector so you can easily grab all the models you want to add to the list.
Select all the models and drag them into the "Models" field.
At Start, the script will choose a random model to activate.
You can leave a model active so it's easy to see where this character is in the scene; it'll be automatically deactivated (and possibly reactivated).