Terraria Wiki → NPCs (Part 2)
Mechanic - If you enjoy fiddling with wires and pressure plates in Terraria, the Mechanic will be a great addition to your arsenal.
Stylist - you can buy hair dye from her and change your character's hairstyle.
The Witch Doctor - a refilling table, a witch's table, and a blowgun that allows you to collect seeds.
A painter helps make your home more stylish and modern. You can buy wallpaper and a roller for hanging/painting walls from a painter.
Party Girl - this NPC is contacted if you need to organize some kind of celebration.
Dye seller - you can exchange plants for rare dyes and buy a dye barge to produce them.
Wizard - sells mana restoration potions and a crystal ball. An indispensable NPC for mage-type characters.
Steampunker - sells gears and a new set of logic sensors. Appears after defeating one of the mechanical bosses: Gemini, Annihilator, Skeletron Prime.
Truffle - appears in the man-made mushroom biome once you've entered Hardmode by killing the Wall of Flesh in Hell. Sells a selection of good weapons and items. To settle Truffle, you need a proper house in the mushroom biome.
NPCs: (Part 1) (Part 2)
See also:
The game's TOP 5 rare terraria items
Quests in Klamath. The world of Fallout 2
Walkthrough: S.T.A.L.K.E.R.: Call of Pripyat.