He's the old man with the curse. He comes at random and sells random items, some of which are very handy. Mass-NPC deaths can take time to recover from as they move back in gradually, so it's something you'll sometimes want to prevent. My Guide was started on Sept 23, and now includes dozens of pages about the game. Those few that are PC-only are marked as such.
Kristen. Age: 31.
Some of them can be found while exploring the game's various areas underground, while others will move in once certain requirements are met.
Bella. Age: 26.
Summon one with a Pirate Map found from creatures in the Ocean Biome. NPCs who are killed during fights will often respawn the next day. He comes at random and sells random items, some of which are very handy.