Guide

The guide is the first NPC that you encounter. His tips are mainly for new players to learn the basics of the game. He, unlike other NPCs, does not need a room to stay in at the beginning, but will move into the first one you build.

Guide's Tips:
"You should stay indoors at night. It is very dangerous to be wandering around in the dark."

"Underground are Crystal Hearts that can be used to increase you max life. You will need a hammer to obtain them."

"If you gather 10 Fallen Stars, they can be combined to create an item that will increase your magic capacity."

"Stars fall all over the world at night. They can be used for all sorts of usefull things. If you see one, be sure to grab it because they disappear after sunrise."

"For a nurse to move in, you might want to increase your maximum life."

"If you had a gun, I bet an arms dealer might show up to sell you some ammo!"

"You should prove yourself by defeating a strong monster. That will get you the attention of a dryad."

"You can make a Grappling Hook from a hook and 3 chains. Skeletons found deep underground usually carry hooks, and chains can be made from iron bars."

"If you see a pot, be sure to smash it open. They contain all sorts of useful supplies."

"There is treasure hidden all over the world. Some amazing things can be found deep underground!"

"Smashing a shadow orb will cause a meteor to fall out of the sky. Shadow orbs can usually be found in the chasms around corrupt areas."

"They say there is a person who will tel you how to survive in this land... oh wait. That's me."

Controversy
The Guide is disliked among many players of Terraria. If you do not own a house with NPC prerequisites, the guide will walk around the spawn area, and will open any doors he may pass without closing them, usually letting monsters in to any home-in-progress (much to the frustration of a player). He is the only NPC that is invincible to monsters. The only proven way to kill him is to trap, chasm or kill him with a bucket of lava.