Villagers are an idea to make Terraria town and villages feel more complete. The landlord would move in randomly, after enough npc's are found. From this NPC, you can buy a for-sale, which when placed in an empty house, causes a villager to move in. These villagers would be randomly generated like any normal Terraria character, and could have special benefits. If your villagers are kept with to a good content level, (which you can check with the landlord) they will consider getting a job. You can hire villagers willing to work at the landlord, and could have them to do jobs such as farm, hunt, or other things. Tax Collector would also collect more money and generate more for the amount of villagers in your town/city. In general, villagers would make a village feel more complete, and you could have a really cool city or town with tons of villagers living there. There would have to be a limit to not flood the max spawns (perhaps 10-30 or a set-able amount). Hopefully this idea can be added to the future. They could even go to the nurse or talk to other speciality npc's at times.