Demolitionist

The Demolitionist is an NPC vendor that will spawn once the following criteria have been met: Once the Demolitionist has moved into a house, he will sell the following:
 * There is an empty house.
 * You have either a Bomb or a stick of Dynamite in your inventory

The Demolitionist's appearance seems to be based on dwarves from many games, films and works of literature. He is significantly shorter than other NPCs and has a beard. Furthermore, his mining helmet, lantern, and the fact that he sells explosives fits the trope of dwarves preferring underground environments. He and the guns dealer also seem to have a rivalry.