I have two characters that occasionally make appearances, and others that ended up background characters. I have a white wolf character whom I can't actually remember if he started as PC or NPC, but has been both at various times, and is one of my favorite characters. Then I have a fallen-rerisen jedi that makes appearances in either SW or D&D games, merely as a bar-contest being.
I also have a god from another game that made his way into my world, along with my PC who brought the worship of that god to the world. He's never actually been seen in play, but he's there in the background.
I also have a god from another game that made his way into my world, along with my PC who brought the worship of that god to the world. He's never actually been seen in play, but he's there in the background.