Here you can learn about all of the different NPCs in The Sims 3.
NPC's are "Non-Playable Characters" or "Non-Player Controled" Sims.
These include Service NPCs such as the Maid and Policeman as well as
Townies, and Special NPCs such as the Grim Reaper and Ghosts. Most NPCs can be socialized with and even moved in, but they lose their status as a burglar or maid, etc. and become more or less unemployed normal Sims.
List of NPCs...
| Autonomous NPCs Burglar Driver Mail Carrier Newspaper Delivery Repoman | Service NPCs Baby-Sitter Firefighter Maid Pizza Delivery Police Repair Technician Social Worker | Special NPCs Ghosts Grim Reaper | Townies Townies |
Autonomous NPCs

Autonomous NPCs cannot be hired, but instead provide a service, or carry out deeds or their own without being summoned by the player. Most NPCs can be social and befriended whether their automous purpose is good or bad.
Burglar
Burglars are mischievious Sims who may sneak up and break into your house at night and try and steal some objects. If there is a burglar alarm in the room, the burglar will panic and the police will arrive automatically and apprehend the burglar. If there is no burglar alarm, you will need to have your Sim manually call the police with the phone, which may give the burglar time to escape. When a burglar is apprehended, the police officer will leave the burglar standing beside the police car outside whilst he or she looks around the house for stolen objects to return. During this time, you can click on the burglar and have your Sim let him or her free. The burglar runs off, but becomes an acquiantance of your Sim and you can invite them over another time for socialization.
Schedule: One Time
Purpose: To steal objects from your Sims' homes.
Gender: Male, Female
Age: Young Adult, Adult, Elder
Socialable: Yes
Marriable: Yes
Special Traits: Burglar
Game: The Sims 3
Driver
Drivers are non-socialable NPCs who only exist to drive your Sims to other places in the taxi, carpool, school bus or other method of transport. They never come out of their vehicles.
Schedule: Whenever your Sim needs uses the bus, carpool, taxi or other unowned vehicle.
Purpose: To drive your Sims to other places.
Gender: Male, Female
Age: Young Adult, Adult, Elder
Socialable: No
Marriable: No
Special Traits: None
Game: The Sims 3
Mail Carrier
The Mail Carrier will come by every couple of days to deliver the mail such as bills and packages such as cut gems and ingots. After delivering the mail, the Mail Carrier will linger for a few moments, giving your Sim time to socialize with them so they can invite them over later.
Schedule: Daily
Purpose: To deliver mail.
Gender: Male, Female
Age: Young Adult, Adult, Elder
Socialable: Yes
Marriable: Yes
Special Traits: None
Game: The Sims 3
Newspaper Delivery
Each day your Sims receive a free daily newspaper which they can read to find a job, find out what's happening in the neighbourhood, etc. There's only one way for them to obtain this newspaper, and that is for the newspaper delivery person to deliver it. Every day the newspaper delivery kid will place a new newspaper near your Sims' front door. After delivering the newspaper, he or she will hang around for a few moments, giving your Sims time to socialize with them.
Schedule: Daily
Purpose: To deliver the newspaper each day.
Gender: Male, Female
Age: Child, Teen
Socialable: Yes
Marriable: No
Special Traits: None
Game: The Sims 3
Repoman
When your Sims don't pay their bills on time, the Repoman will arrive at your lot and take away enough objects to meet the owed amount of money. He will go from room to room sucking up objects to meet the required amount. After taking enough objects, your Sims have a chance to socialize with him for a few moments before he leaves. Though the relationship isn't off to a good start, you can later invite him over and socialize with him further. (Who would want to befriend the repoman?). The repoman won't repossess essential objects like the fridge and the toilet, but if there is not enough objects for the repoman to repossess, he will simply take the money from your family funds.
Schedule: One Time
Purpose: To repossess objects when Sims don't pay their bills.
Gender: Male
Age: Young Adult, Adult
Socialable: Yes
Marriable: Yes
Special Traits: None
Game: The Sims 3
Service NPCs

If your Sims make a lot of mess in their everday lives by not cleaning up their dishes, not making their bed, etc. and they don't have time to clean up after themselves, a maid will do the job for them, but for a price.
If your Sims want a pizza takeaway, calling the Pizza Delivery on the phone via the services menu will send a Pizza Delivery Person to the lot with your Sims' pizza. After delivering the pizza, the delivery person stays on the lot for a few moments, during which your Sim can ask them to hangout or chat with them, and you can later invite them over personally to build the relationship. Eating a pizza gives your Sims the Amazing Meal moodlet.
Repair Technicians can be hired to fix any broken objects in your Sim's house. There is a 1% chance when fixing a broken electrical object that the Repair Technician will be electrocuted and die. After fixing all objects, your Sims can socialize with the Repair Technician for a few moments before he or she leaves, and you can later invite them over again personally for more socialization.
If your Sims want to adopt a child, they can call up the Adoption Service, and a Social Worker will come by to drop off the child. When the Social Worker arrives, you get to choose what gender and age you want the child to be. You can adopt a baby, toddler or a child. After dropping off an adopted baby, your Sims can socialize with the Social Worker for a few moments before they leave, and invite them over later. The Social Worker will also remove neglected children from the family. If a baby, toddler or child is neglected for too long, after a couple of warnings beforehand, the Social Worker will come by and remove the child. You cannot socialize with the Social Worker at all when they are removing a child.Special NPCs

Ghosts
Your Sims might think the death of their loved ones is the last time they will ever see them. Well they are wrong. When a Sim dies they are given a gravestone or urn. If the grave is kept, the dead Sim may appear at night as a ghost. Your Sims can socialize with ghosts, and become friends with them, but cannot marry or move them in. Head to the graveyard sometime after midnight and be sure to find some ghosts. A new ghost appears in the graveyard roughly every hour. You may even find them roaming the streets at night, or even driving a car. Ghosts can become playable through a special event if you have a grave on your lot. Find out more on the Creatures page.
Time: Midnight - Dawn
Purpose: Haunt and Roam Around the Graveyard or House.
Gender: Male, Female
Age: Child, Teen, Young Adult, Adult, Elder
Socialable: Yes
Marriable: No
Game: The Sims 3
Grim Reaper
When a Sim dies, the Grim Reaper will appear to take the Sim into the afterlife. When the Grim Reaper lingers on the lot after taking the dead Sim away, your Sims can socialize with him. You can even become friends with the Grim Reaper. The Grim Reaper has the Kleptomaniac, Brave, No Sense of Humor, Neurotic and Mean Spirited traits. Sims can also challenge the Grim Reaper to a game of chess whilst he is on the lot. If they win, they live, but if they lose, they die.
Time: Whenever a Sim dies.
Purpose: To take dead Sims to the afterlife.
Gender: Male
Age: Adult
Socialable: Yes
Marriable: No
Game: The Sims 3
Townies

Townies are NPCs who look like normal Sims, but don't actually live in the neighbourhood. They are fully socialable just like your own Sims and can be befriended, moved in or even married. Their appearance is somtimes rather strange due to being randomly generated.