Each survivor can have a number of perks (normally up to 4) which provides various bonuses, such as additional skill points or increases effectiveness with certain missions. The main leader has a special perk chosen at the start of the game which affects the entire fort. Some survivors arrive already with perks. Most perks are gained when a survivor reaches level 3, 6 or 9, after you talk to them and learn more of their backstory.
Main Leader Perks
Politician
+leadership and one extra survivor
Shop Clerk
+scavenging and +25% trade bonus
Doctor
+science and -1 day injury recovery time
Retiree
+building and +10% happiness bonus
Police Officer
+offence and +1 level bonus from all firearms
Negotiator
Bonuses while trading with factions
Preacher
More effective while working in a church
Entertainer
Bonus happiness to others during missions
Firearms Training
+1 Defense with anything from pistols to machine guns
Melee Training
+1 Defense with anything from a shovel to a sword
Hand to Hand Combat
+2 Defense when no weapon equipped
Demolitions
Explosives do extra damage
Hoarder
Extra building materials while scavenging
Good Cook
Bonus food production
Green Thumb
Bonus food while farming
Redecorator
May automatically convert useless buildings
Defenses Expert
Grant +1 defense to all buildings
Artist
Happiness bonus when fortifying buildings
First Aid
Reduces chance of death on missions
Bookworm
Researches faster, bonus from equipping books
Crafter
Creates more items in the workshop
Positive & Tradeoff Perks
Half Rations
Eats less than other survivors
Animal Lover
Extra skills and happiness if equipped with a pet
Easy Going
Double happiness increases and halve decreases
Superdude
Increase each skill by 1. Increase max levels by 1.
Loner
Improved skills when on a mission alone.
Team Player
Improved skills when on a mission with at least 3 survivors
Fast Recovery
Recovers from injury faster
Ninja
No penalty for how far away a mission is.
Devout
Extra happiness from churches
Camper
Sleeps under the stars, does not need a house
Driver
Does missions faster when equipped with a vehicle
Scholar
Learns more from schools
Skeptic
+1 engineering, immune to religion
Stinky
+1 defense, but hard to make friends
Brave
+1 defense, but may take the hit for another survivor
Tough
Less likely to die, but hard to make friends
Pacifist
Increases relationship with factions, but can't use weapons
Coward
Less likely to be injured, but -2 leadership
Light Sleeper
+1 to all building defense, but half happiness increases
Eccentric
Makes both friends and enemies easily
Negative Perks
Double Rations
Eats more than other survivors
Allergic to Pets
Can't equip animals
Clumsy
Increased mission danger
Sickly
More likely to get sick
Downer
Lowers happiness of other survivors when on missions
Rebellious
May refuse to work
Item-Based Perks
Pet Owner
+10% Happiness
Vehicle
Removes mission danger from distance.
Faction Perks
Former Riff
Increases sway with the Riffs faction
Last Judgement Escapee
Increases sway with the Riffs faction
Former Chosen One
Increases sway with the Chosen Ones faction
Former Pig Farmer
Increases sway with the Pig Farmers faction
Former Luddie
Increases sway with the Luddies faction
StMicheals Dropout
Increases sway with the StMicheals faction
Rotten
Increases sway with the Rotten faction
Government Defector
Increases sway with the Government faction
Former DAHLIA
Increases sway with the Riffs faction
Former 1337cREw
Increases sway with the 1337cREw faction
Former Pharmacist
Increases sway with the Pharmacists faction
Friend of Gustav
Increases sway with Gustav the trader