Let's see. I'm gonna see if I can pull up the history behind every title.
First a little bit about the titles (since people keep asking about it). The idea of giving people titles came up first during the end of Mafia V, when Niccea was titled "The great deceiver", during the endgame narration. As Mafia VI progressed, more titles were given and eventually it became a habit. In theory, there are no rules about how a title is earned but it is generally frowned upon that the players themselves suggest their own titles. Who gets a title is rather random but it usually occurs when a player does something that stands out so much that bemused players suggest a title for him. If other players like it, it sticks. Play the game enough and you might get one too.
TheFlyingGreenMonkey. Became the everlasting Pardoner, when he won the pardoner role for the fourth time in a row. Became a Bringer of Bloodbaths after killing off the entire town as the serial killer. Game VII
Gullas became known as the Impaler when he got the role of the vigilante and ended up killing more townies then the criminals did. Is a terrible gambler for making one of the worst bets in history of mafia games.
harkovast the Patron Saint of Finger Pointing. Got that for his relentless blame throwing in the early games. The title "Self Proclaimed Furry Pusher" is the only time where a player managed to suggest his own title, partially. Mafia XVIII GM election.
jninjashadow the Town Drunk. For roleplaying a drunk person.
rokulily the Minister of Cuteness. Because she's just that cute.
Product Placement the Game Master. Part because I've hosted more mafia game then any other players. Part because I run them pretty well.
Salsa the Luckless. Every time he got a criminal role, he ended up getting himself killed or lynched out of bad luck. It was never the clues that got him but usually he said something in the forum that made people lash out at him or suspect him.
Niccea the Great Deceiver. One of the first titles. In game V, she became the Godfather and won the election, becoming the mayor as well. The town never suspected a thing until it was too late. She was also titled as the Keeper of Records since she's responsible for the mafia comic and all related knowledge.
I Am The 1337 Is the god damn Batman because I've never seen a more successful vigilante. He lived for 4 nights and attacked a criminal, every night.
ParkerFarker the Crazy Glow Stick Stabber. Based on one of FlyingGreeenMonkey's narrations.
Anthony Mercer the Emotional Lurker. Never said anything in one of the games and was upset about being lynched.
crocty became the Usual Suspect because he was ALWAYS getting a mafia role. So often did he get it that players automatically started to suspect him of being mafia at the start of every game.
hakoshen is the spartan because he made brutal narrations as a GM. First mentioned Game IV
Waff-Man. He's the homeless caped crusader of townston. Got that title for being an interesting vigilante. Game IV
Exzachly the smuggest. Won the smuggest competition against harkovast.
Retaya the dramatic. She only had to kill one more person to win the game for the town but she kept procrastinating in order to make the game more exiting (by making the other players believe that the bad guys were about to win).
Aghammer the Explosive. Helped destroy the town as a mad hatter variant.
Pastel the Mass murderer. Got that for being the first serial killer to win a game (by being the last person standing).
That's all the titles I can think off (and research).
Ya know, I just realized, maru was the only Rager alive. I nominate her for the title: maru the Last RagerYou know what? That one ain't that bad.
