Saw these during different Mafia Games.
Arsonist - Once per Night, the Arsonist can drench someone in Gasoline, including him/herself.During a different Night or on the Day Phase, they can kill all targets they have drenched by setting them on fire.
Jailor - During Night Phase, the Jailor can put a player of their choice into prison and is allowed to question them during the Night one on one.All other roles which target that player are nullified.The Jailor himself is excluded and has the option to kill the Prisoner.During the switch from Night to Day Phase, the Jailor dies if he had inprisoned a Serial Killer and did not kill him.
Survivor - The Survivor is a Town Member with 3 Bulletproof Vests available.During the Night Phase, he can put one on and is safe from attacks.After all 3 are used, he becomes a plain Town Member.
Lookout - The Lookout is a Townie who can choose to keep an eye on another player during the Night Phase and can see which player has been visiting them.
Executioner - A neutral player role who's sole goal in the game is to get one other randomly picked player killed.Whoever is winning or losing does no matter for them.Whether by lynching, mafia kill, serial murder kill etc. does not matter as long as they die.
Jester - A Jester is a neutral player who solely wants to get lynched out by any means.If the Jester is lynched, he can choose one player who voted for him to curse them and is killed along with them.
Mafia Blackmailer -A Mafia Member who during Night Phase chooses a player who during Day Phase is forced to say something chosen by the Blackmailer, or forces them to not say something specific.This can only be used once during a game and afterwards he becomes a normal Mafia Member.