An NPC (non-playable character) is an automated character that provides some service to players. Players can utilize NPCs by standing near them and right-clicking on them.
Most NPCs are vendors, providing items in exchange for coins (and coins in exchange for items). Exceptions are the Guide, who provides information, and the Old Man, who is used to summon Skeletron. The Nurse, who doesn't sell items, provides Health restoration in exchange for coins instead. The Goblin Tinkerer sells items, but also provides the Reforge function.
Most NPCs require a suitable, vacant Home built by the player. This is a confined room (completely enclosed by walls, wooden platforms or doors) with background walls, and certain furniture and space requirements. See Home for details.
Most NPCs also require that their specific conditions are met, usually meaning the player must achieve a certain level of advancement in the game. Examples include acquiring 50 silver coins for the Merchant to spawn, or beating your first Boss for the Dryad to appear. See the specific NPC requirements in the table below.
NPCs can be assigned to suitable homes using NPC Flags from the Housing Menu, where you can also check whether a room is a suitable home. Currently though, the Housing Menu checking tool is glitchy, reporting suitable homes even when some conditions are not met. Refer to Home for more extensive details.
The Guide and Old Man are unique in that they always spawn upon creating a world. The Guide will also move into the first home you build. If he dies, he will need a proper home to respawn. The Old Man does not move into built homes, but always appears near the Dungeon's entrance, and respawns the following day if killed. He despawns permanently once Skeletron is defeated.
NPCs will take about 2 minutes to spawn after another NPC has spawned or dawn passes.
All NPC vendors can be used to sell your unwanted or surplus items to gain coins, simply by placing your unwanted item(s) in their inventory. Not all items have a sell value (very common items like Dirt or Wood, for example, have no value). Hovering over your item while the NPC's inventory is open will show its sell value. All NPC vendors offer the same amount of coins, at all times, for any given item.
Should you change your mind about a sale, sold items can be taken back in exchange for the amount you sold them for, as long you haven't yet closed the NPC's inventory screen. This does not hold true for items you purchase from an NPC's inventory, as purchases are permanent, and re-selling will not get you back the full amount you paid (sell value is always one fifth of its buy value).
Right-clicking an item will allow multiple purchases rather than purchasing it one by one.
- NPCs living in houses reduce the spawn rate of enemies in the area, and the more NPCs you have in an area, the fewer monsters will spawn. This effect, however, is nullified by the Blood Moon.
- When night begins, NPCs will walk into their houses and remain there until dawn, at which point they will walk around again and move through doors.
- If a house occupied by an NPC is destroyed, the NPC will move out, but will walk around in the same area and will no longer stay still at night, until the house is restored, a new one is built, or the NPC is killed (when he will not respawn again until a valid, vacant House becomes available again).
- All NPCs have finite health and can take damage from enemies, though their health automatically regenerates over time, and a killed NPC will respawn and move back into a suitable house.
- It must be daytime for any NPCs to spawn.
- Bound NPCs found underground can be freed by talking to them, after which they will always respawn whenever a vacant house is available. Having an empty room ready for them when you anticipate finding one will mean you will have convenient access to them from your Town earlier on, though this is not required, and building a house later will still cause them to spawn at that time.
- NPCs will not spawn during an active/undefeated Goblin Army or Frost Legion.
 List of NPCs
|The Guide spawns with the player when they start a new world. He provides tips and crafting recipes.|
|The Merchant is acquired when all players combined have more than 50 in their inventories. He sells certain basic tools.|
|The Nurse is acquired when you have found and used a Crystal Heart to increase your life capacity above the initial 100. She can fully heal players in exchange for coins.|
|The Demolitionist is acquired when you have an explosive in your Inventory and at least one Merchant is present. He sells explosives, and, in hardmode, Hellfire Arrows.|
|The Dryad is acquired when you have beaten a Boss other than King Slime. She buys and sells certain nature/corruption items, and can tell the player the percentage of Corruption and Hallow in the world.|
|The Arms Dealer is acquired when you have bullets, or a gun that shoots bullets, in your inventory. He sells certain guns, bullets, and Unholy Arrows.|
|The Old Man is found at the entrance to a Dungeon. He summons Skeletron, but only at night. Once Skeletron is defeated, the Old Man is no longer present, as it can be inferred that the curse he was afflicted with is removed and he becomes the Clothier.|
|The Clothier is acquired after you defeat Skeletron. He sells certain Vanity items, including the Familiar clothes. Note: Once the Clothier arrives, the Old Man despawns permanently (they are believed to be the same person).|
|The Mechanic is found bound in the Dungeon. She sells wire and other mechanical items|
|The Goblin Tinkerer is found bound somewhere underground after defeating a Goblin Invasion. He sells items such as the Tinkerer's Workshop, and can reforge tools and equipment.|
|The Wizard is found bound somewhere underground after defeating the Wall of Flesh. He sells certain magical items.|
|Santa Claus can be acquired between December 15th and 31st after you defeat the Frost Legion. He sells the Santa costume and coloured lights.|
 Multiple NPCs
Note: This relates to a feature that was now deleted, although it has been confirmed that it will return on The Last Update by a developer's twitter account Source?
|A second Merchant is acquired by having three players with a combined wealth of at least 50 .|
|A second Nurse spawns when there are at least three players with a combined health of 400HP|
|A third Merchant appears when there are at least five players with a combined wealth of 5 .|
- 1.1.1: Bound NPCs now can be untied with Autopause enabled.
- Santa Claus Introduced
- NPCs now have random names given to them on spawn. Their deaths will be reported with these names. Also other NPCs will use them in their quotes.
- NPCs now may be told where to live using the new housing menu feature.
- Two NPCs of the same type can no longer spawn, even on a multiplayer world. (Previously that was two additional merchants and second nurse. They had multiplayer conditions.)
- 220.127.116.11: NPCs now look at the character.
- Shops now sell items back to you. Shift-clicking items will automatically sell them.
- New sound for initiating a conversation to an NPC.
- 1.0.4: Added an option that will pause the game while talking to an NPC in single player. It defaults to off.
- Pre-Release: Introduced.