My witch doctor died. What needs to be done or what criteria need to be met for him to respawn? I tried building an additional house to no effect.
EDIT: My information about spawns was incorrect. It has been corrected.
The Witch Doctor only requires that the Queen Bee has been defeated and a house is available. Be sure that the Queen Bee has been defeated in the current world, and use the housing menu to check that the house is valid for NPCs. It may take a few game days for the WD to respawn after dying.
The information below regards the Witch Doctor having additional shop inventory in a jungle.
The Witch Doctor will only sell certain items in a jungle house (and again, only after the Queen Bee has been defeated). You have two options here:
Build a permanent house for the Witch Doctor in the jungle. This is the easy option.
Add mud blocks and jungle grass into an above ground house to make that area qualify as jungle. This is the more convenient option, but will take longer.
You'll be able to tell that the house is "jungle" because the background and music will change to the jungle theme.
Edit: The official wiki does not mention the jungle requirement, so here are some unofficial resources. Image of an example Witch Doctor house (bonus Truffle housing): http://s23.postimg.org/3ytg3753f/biomes.png
Steam user asking a similar question: http://steamcommunity.com/app/105600/discussions/0/810938082072494361/