Image from gallery.

Hiya.
In my game, I’d like the player to import an image from their gallery to be used as their avatar in-game. Is this possible in unity, without using a plugin? If not, where can I find a suitable, free plugin that can do this?

Your question doesn’t specify a platform, but assuming you’re referring to iOS or Android, there is no way to do this without a plugin.
Luckily for you, there are several plugins in the asset store that will help you with this.
My favorites are
Unity Asset Store - The Best Assets for Game Making and
Unity Asset Store - The Best Assets for Game Making
But are paid.

You may want to give this one a try if you really don’t want to fork out the cash, but I haven’t tried it so I can’t recommend it one way or another.