I'll post a bunch of role ideas. If you have any to add, reply and I'll add it to the list if it isn't stupid.
Town
King
The king will receive a one-use bulletproof vest. When there's a king in the game, there are no lynch votes in the day cycle, only discussion. At the end of the cycle, the king will decide who to lynch. The king holds the one and only vote for lynching. If the people are dissatisfied with the king, they can vote to stage a coup during the day cycle. If a majority vote on this is reached, then the king will be put on trial/lynched, and no other person will be lynched on that day. The next day cycle after a coup, the citizens will vote on a new king. The first king to be chosen is guaranteed to be innocent, but elected kings may or may not be mafia!
Hunter
The hunter receives a single-use bear trap that he can lay down during any night cycle. If somebody visits the Hunter at any night after the trap is laid, then they will be trapped. The next day cycle, the trapped player is publicly revealed as trapped, but their purpose for visiting the trapper is not revealed. The trapper then becomes a normal townie.
Spy
Every night cycle, the spy is able to view the mafia chat. No names or other identifying features are shown, only the raw text.
Forensics Investigator
Every night cycle, the forensics investigator is able to investigate a body. The investigator will get a complete list of the roles, but not names, of who the person was visited by, and the names of everyone that the person visited.
Cursed Townie
The night after the Cursed Townie is killed, he will be able to appear to a single player and speak to them for the duration of the night.
Operator
Every time someone sends a private message, the Operator will be informed who sent the message, and who received it.
Wiretapper
Every night, the Wiretapper selects a target to wiretap. The following day and night, all private messages sent and received by the target will be revealed to the Wiretapper.
Priest
The priest can either condemn or bless a player. When a player is condemned, they will require one less vote to be lynched/put on trial. When a player is blessed, they require one more vote to be lynched/put on trial. Whether or not the player and/or the town are notified to a player's cursing/blessing is left up to the host.
Friendly Neighbour
Every night, the Friendly Neighbour can visit another player's house. That player will be informed of the Friendly Neighbour's innocence.
Naive/Paranoid/Crazy/Inexperienced Cop
These "special" cops are not told of their true role, only that they are cops. Naive cops will get an innocent result on every player investigated. Paranoid cops get a guilty result on every player. Crazy cops will get opposite results on the player's role. Inexperienced cops will get completely random results.
Mafia
Thug
The thug doesn't participate in the mafia night chat, and does not know the identities of the other mafia. After the other mafia have decided on a target, the thug will carry out the kill. This means that any roleblocking, tracking, or other such actions will specifically affect the thug. If there are multiple thugs, a random one is chosen as the killer. There will also be the toggleable option of the mafia not being able to carry out any kills if all thugs are dead.
Usurper
The Usurper acts as if a normal mafia, but with an extra role. The Usurper has to try to get the Godfather lynched. If the Godfather is lynched, then the Usurper will become the new Godfather. If the Godfather survives to the end, the Usurper loses, even if the mafia win.
Frame Artist
At night, you can frame one person. That person will then give a "guilty" result on any investigations done on them.
Forger
Every night, the Forger can set the last will of another player.
Neutral
Jester
The jester is trying to get lynched. If he is lynched, then he can choose a person to take with him.
Arsonist
Every night, the Arsonist douses a target in gasoline. During any day cycle, the Arsonist can anonymously light a fire, killing all the people he doused.
Other
Werewolves
The werewolves are a second "faction" of mafia. The analogue of the godfather is the alpha werewolf. Werewolves have the same goals as Mafia. There are also two new roles, Seers, which act as Cops, and Angels, acting like doctors. Angels will protect people from Werewolves, but NOT from Mafia, and the Doctor will NOT protect from Werewolves. Likewise, Seers only detect Werewolves as guilty, and Cops only detect Mafia as guilty.