Here are the results for the normal edition of the game, without the coven expansion:

Vigilante, Veteran, Mafioso or Ambusher
Medium, Janitor, or Retributionist
Survivor, Vampire Hunter, or Amnesiac
Spy, Blackmailer, or Jailor
Sheriff, Executioner, or Werewolf
Framer, Vampire, or Jester
Lookout, Forger, or Witch
Escort, Transporter, Consort, or Hypnotist
Doctor, Disguiser, or Serial Killer
Investigator, Consigliere, or Mayor
Bodyguard, Godfather, or Arsonist

These are all the different results with the Coven expansion:

Vigilante, Veteran, Mafioso, Pirate, or Ambusher
Medium, Janitor, Retributionist, Necromancer, or Trapper
Survivor, Vampire Hunter, Amnesiac, Medusa, or Psychic
Spy, Blackmailer, Jailor, or Guardian Angel
Sheriff, Executioner, Werewolf, or Poisoner
Framer, Vampire, Jester, or Hex Master
Lookout, Forger, Juggernaut or Coven Leader
Escort, Transporter, Consort, or Hypnotist
Doctor, Disguiser, Serial Killer, or Potion Master
Investigator, Consigliere, Mayor, Tracker, or Plaguebearer
Bodyguard, Godfather, Arsonist or Crusader

** Update: In update 3.2.5 [The NK buffs], the unique role Juggernaut is now added to the Investigator results to make it not instantly found out.

It's always important to keep a will in this game if you don't already, because people in this game will devour you if you don't keep a will.

Here's the most basic version of a will you can have, that you can follow pretty easy. It's pretty basic, though.

[Name] - [Role]

n1 : [Who you visited] - [Results]
n2 : [Who you visited] - [Results]
n3 : [Who you visited] - [Results]
n4 : [Who you visited] - [Results]
n5 : [Who you visited] - [Results]
n6 : [Who you visited] - [Results]
n7 : [Who you visited] - [Results]


Sample Will:

Kappa - Investigator

n1 : William - Vigilante, Veteran, Mafioso
n2 : John - Bodyguard, Godfather or Arsonist
n3 : Dan - Medium, Jaintor, Retri
n4 : Shawn - Survivor, Vampire Hunter, Amnesiac

Another sample will: (Commented by "Multihack")

Last will and testament of <>

TI -
TI -
TP -
TK -
TS -
RT -
RT -
RT -
NE -
NK -

Here are all the possible alignments in the game, with all the roles and the nicknames/ abbreviations for the roles.
(+ Icon = New Roles with the Coven Update)

Town Protective (TP) - Doctor (Doc), Bodyguard (BG), Crusader (Crus) (+), Trapper (+)
Town Support (TS) - Escort (Esc), Mayor, Medium (Med), Retributionist (Retri), Transporter (Trans)
Town Investagative (TI) - Sheriff, Investigator (Invest), Spy, Lookout (LO), Tracker (+), Psychic (Psy) (+)
Town Killing (TK) - Jailor, Vampire Hunter (VH), Veteran (Vet), Vigilante (Vig)
(Mostly Town are initialed, and on Ranked there is just random mafia, which can be any of the role below:)
Mafia Killing - Godfather (GF), Mafioso, Ambusher (+)
Mafia Support - Blackmailer (BM), Consigiere (Consig), Consort
Mafia Deception - Disguiser (Disg), Forger, Framer, Janitor (Jan), Hypnotist (Hypno) (+)
Neutral Benign - Amnesiac (Amne), Survivor (Surv), Guardian Angel (+, GA)
Neutral Evil - Executioner (Exe), Jester (Jest), Witch
Neutral Killing - Arsonist (Arso), Serial Killer (SK), Werewolf (WW), Juggernaut (Jugg)
Neutral Chaos - Vampire (Vamp), Pirate (+), Plaguebearer (Pb, +), Pestilence (Pest, +)
(Coven Exclusive)
Coven Evil - Coven Leader (CL, +), Hex Master (HM, +), Poisoner (+), Potion Master (PM, +), Medusa (desu) (+), Necromancer (+, Necro)

Fun Fact: Jailor says Town Killing, but if there is already a Jailor on the role list, there can't be another jailor. Jailor is a unique role (along with: Godfather, Mayor, Retributionist, Veteran, Mafioso, Ambusher (+), Juggernaut (+), Plaguebearer (+), Pestilence (+), Pirate (+), Werewolf, Coven Leader (+), Necromancer (+), Medusa (+), Potion Master (+), Poisoner (+), Hex Master. (+)) There can not be two of these roles in a game, even in custom.

Edit: You can also check this in game by just clicking on the role list... also you can see the description of each role! Pretty neat. Now this section is somewhat pointless, besides the abreviations.

Edit 2: Added some more will abbreviations, thanks to therobertor2000 for that.

Edit 3: Added a few more role abbreviations, thanks to ElementalWAFE and KaneTheBoom!

Credit goes out to the Town of Salem Wikia, without it it would have been a little bit tricky to make this guide. TOS Wikia [town-of-salem.wikia.com]

If you guys want another guide similar to this, please just tell me what I should do and leave it in the comments. Also, if you see any errors, you are welcome to tell me in the comments and they will be fixed. Thanks alot <3.