NPCs

NPCs (Non Player Characters) are people in the game you can benefit from. All NPCs that move in need a house 6 blocks of empty space tall, and 10 wide. They also need a piece of furniture and a chair (usually a Work Bench and a Chair), a suitable light source, and walls.

List of NPCs
The Guide

Spawns with you when you create a new world. In order for him to move in, you need a suitable house.

The Merchant

Comes when all players in the world have a combined amount of 50 silver coins, and a suitable house.

The Nurse

Comes when a player in the world has used a Life Crystal, and a suitable house.

The Demolitionist

When a player has an explosive, such as a Bomb or Dynamite, and a suitable house.