Survivor
A Survivor is a human NPC that has survived the initial infection and is trying to survive the Knox Event.
Kate Smith
Kate Smith Smith is a NPC that is spawned at the start of the game in 'Til Death Us Do Part. She broke her leg when fleeing from hostile survivors, and is cared by Bob Smith (the player). She doesn't need any food or water to survive, but she is still capable of dying of damage or by smothering by a pillow. Kate Smith is the only survivor spawned with an injury, and she is not capable of moving, although her bleeding will slowly recuperate. She is suppоrtive of Bob, and cares about him deeply, going as far as telling him not to risk going outside at night because he might die.
If the player wishes that he wants to skip the tutorial, he can kill Kate by either smothering her with a pillow or attacking her with a weapon. If Kate is killed, the safe house music will change and Bob will get a picture of Kate. All the scripted events will be canceled, and Bob will be forced to roam Knox County alone, without a tutorial and without the pre-determined NPCs.
Gun Nuts
In Project Zomboid, gun nuts are special NPCs who are always hostile towards the player. They will attack at sight, and they will only spawn at pre-determined locations at the start of the game.
'Til Death Us Do Part
In 'Til Death Us Do Part, exactly two Gun Nuts will spawn in the world. They are Jack Bloggs and Bobby Collins. More information of what they do to the player or what they say can be found at the 'Til Death Us Do Part article.
Bobby Collins
Bobby Collins a cruel yet well-prepared man who roams Knox County, looking for a home. Bobby has a shotgun, 18 shells, a baseball bat, a vest, a trouser, and a lighter, which is loot able by the player after he is dead. After cooking a Pot of Soup, the Smith family will receive a transmission from a radio, and Bobby Collins will spawn sometime during the transmission. Bobby will then make his way into the Smith house, and will threaten Bob or Kate with a shotgun, and will kill them both if Bob doesn't intervene. If Bobby is stopped, the tutorial spawn limit will be gone, and the player will have to survive as if the game were Game modes
Jack Bloggs
After completing the tutorial, you can find a survivor in the supermarket. He is armed with a shotgun, and will warn Bob to leave the supermarket. If Bob doesn't leave, he will shoot Bob, but if Bob kills him while he is warning him, Bob will be able to steal his belongings, which are a shotgun, a sweater, a trouser, 18 shells, a baseball bat, a lighter, and some other supplies.
Other Survivors
The survivors listed in this category can spawn in both the sandbox and the story mode.
Neutral Survivors
A true neutral survivor is a survivor who will team up with the player if the player has a good attitude. True neutral survivors can then be ordered by a "leader" (usually the player if the group is formed by a player). As of the 0.2.0r RC2.5, they can be ordered to "stay", "follow", or "guard". In addition to that, they will fight or flee from zombies, depending on personalities. The player can give a team NPC items, and the NPC will respond with gratitude.
Loners
A loner is an "initially-neutral" survivor who will spawn naturally in Knox County. Loners will not want to join the player, regardless of the attitude of the player, and any attempt to team up will end in anger in both sides. A loner that is continuously bothered with team requests will fight the player in a duel to death. Other than their team attitude, they will generally act like true-neutral survivors.
Abilities
Survivors get the traits and professions the player also starts with, and they too, can level up skills. Survivors are also given a level of bravery; more cowardly survivors will flee from enemies while braver ones will stand and fight, despite them fighting a hopeless battle.