NPC

An NPC or Non-Playable Character is an automated character that provides a service to players. Most NPCs are vendors, providing items in exchange for coins, and vice versa. Exceptions are the Guide, who provides information, the Nurse, who doesn't sell items, but instead provides Health restoration in exchange for coins, and the Clothier, who provides Vanity clothes. A player can utilize NPCs by standing near them and right-clicking on them.

NPC's have randomly generated names as of 1.1. 400px

Conditions
For all but two of the 12 NPC's (Excluding the Old man and guide at the start of the map) to spawn you must build them a home, which consists of a light source (Items such as disco balls and crystals don't count towards this, but you can set up a torch and a switch, wire them together, turn the torch off, and set up the lighting you want and the torch will be barely visible.), a flat surface, a comfort item, and a table and chair, as well as meeting one other unique requirement for each NPC, which are listed below (More information in the home page) This doesn't exclude the guide, who still requires the same to spawn. NPCs will not spawn if Goblin Army is present, or if your house is on an area affected by Corruption.