Which types of NPCs are safe to play as?

Which types of NPCs are safe to play as? The answers are all here. A basic list of all the different types of playable Sims, townies, NPCs etc. from The Sims 2 and the facts about whether or not they are safe to be made playable. Note that this page may change over time as more information and updates are added. Not all the information here is guaranteed correct, although most of it is apparently true.