Here is a glossary of roles which seem to come up in Scene games on a regular basis. If you have a good idea, or just want to discuss any role, please do so in the Role Discussions thread.

Basic roles
The town
The town (and everyone on the town's side, unless stated otherwise) win when all anti-town roles have been eliminated. Normal townies can only vote during the day and nothing else.

The mafia
The mafia's goal is to eliminate everyone who isn't in the mafia. Like townies they can vote during the day, but may also communicate with each other during the night. Each night the mafia may also attempt to kill a player.

All other roles
The Doctor
Each night the doctor may choose one person to protect. If the protected person is the target of a mafia attack, the target survives. There are variants on the doctor role with regards to whether the doctor can protect himself or not, and whether a protected person is protected from just one attack, or any attack during the night.

The backup doctor
The backup doctor comes into action if/when the doctor dies. When that happens the backup doctor gets the same powers as the doctor had.

The Cop
Each night the cop may choose to investigate a player. The moderator tells the cop whether the investigated person is on the town's side or not.

The backup cop
The backup cop comes into action if/when the cop dies. When that happens the backup cop gets the same powers as the cop had.

The Masons
The masons are two or more players on the town's side who can communcate with each other during the night. Other than that they are just normal townies.

The Vigilante
The Vigilante is a killer on the Town side who can either choose to kill every night, or choose to kill a certain number of times during the game, depending on the variation.

The Role-blocker
The role blocker blocks one player per night from performing his or her night choice.

The Target-switcher
The target switcher may choose two players each night. If the target swticher chooses Alice and Bob one night, then if Alice is targeted, the targeted action gets transfered to Bob.

Snoop
The snoop can check a player's house to find out if they are home (anyone doing something during the night is not home).

Gunsmith
The Gunsmith can check one customer each night, and finds out whether that player has a gun (and people with guns (or other weapons are usually: Mafia, Cops, Detective, Vigilante).

The Bomb
The bomb has a chance of killing anyone killing him. This usually only applies to night-time killings, and not lynches.

The Mortician
The mortician can examine anyone who died during the night to find out information about how they died. This information can then be used to figure out what kind of weapon, and in extension who the killer was.

The Traitor
The traitor is a player on the mafia's side, without being a part of the mafia itself. Usually the Traitor knows who is in the Mafia, but the Mafia do not know who the Traitor is. The Traitor wins if the mafia win.

The Godfather
The godfather is a mafia member who is immune to investigation by the cop.

The Serial Killer
The Serial Killer is a one-man mafia, and can attempt to kill a player each night. To win the serial killer (or SK) has to outlive all other players.

The Cult
The Cult is somewhat of a mafia-like group. But instead of killing, the cult recruits members. The goal of the cult is to take over the whole town (or have anyone not in the cult dead). Please note that this is an extremely difficult role to use in a game because cults can grow very rapidly and may be hard to beat without proper balancing.

Variants
Cop variants
There are a number of cop variants. Among them are those that receive results which may be wrong, those that receive results that are the opposite of the truth (townies show up as mafia and vise versa) and even one that gets "evil" results from all players (or the opposite, with "good" for all players).

Doctor variants
The main variant on the doctor role is an "incompetent doctor" which only has a certain chance percentage to protect someone each night.

Traitor variants
There is a variant of the traitor role where the traitor doesn't know who the mafia are, or even that he is a traitor, but where the Mafia can choose at any time in the game to recruit their Traitor. Before this time, the Traitor appears innocent to Cops, and/or has investigative abilities. Once recruited, the Traitor becomes a normal Mafia member.