Arms Dealer

The Arms Dealer is an NPC vendor that will spawn once the following criteria have been met:
 * There is an empty house.
 * You have acquired a gun.

The easiest gun to acquire for this purpose is the Musket, which can be obtained by destroying a Shadow Orb.

Once the Arms Dealer has moved into a house, he will sell the following:

The Arms Dealer is very arrogant compared to the other NPCs and seems to have a charismatic personality, being (seemingly) able to tell you intend to either buy the Minishark or steal one of his weapons. This, when coupled with the way he speaks, may support that he's based off the traditional gunslinger from old Western movies.