There are a lot of assumed player types; your rules lawyers, your munchkins. A lot of these have changed or been reframed over the years. A rules lawyer can actually be great if you turn them into your rules caddy. The munchkin could help teach the other players how to do better use their abilities.
There’s a role which I keep encountering and encouraging in my groups in the past few years. It’s the “Chaos Engine”. It’s been a phrase some of my players have worn with pride. They know they’re the person who’ll push the big red button or pull the random levers to see what happens. This sounds like it could be disruptive and occasionally it can be, but groups can get stuck. They might look around for something to do, they might be acting too cautious about their plans. At the same time, the Chaos Engine in the group has got bored and already pushed a button or wandered off down a corridor.
In the past I may have viewed this sort of thing as disruptive behaviour and when done with no respect or love for the party it still can be. Most of the time these days, the Chaos Engines I’ve known have been fantastic at initiating plot with their lack of impulse control.
My current incarnation of the In-Fighters has one player, Wade, who is my Chaos Engine. His motto has become, “No one was there to stop me” and that pretty much explains it. In the olden days of D&D I know that a group would have babysat him or lectured the player because they couldn’t count on a slow, cautious attempt at wandering through a dungeon and spending the least amount of spells, HP and so on while trying to get a victory. These days though, the group will load him up and get him to do things on his own as they need someone to do the bad/dumb thing. Sure, he’ll sometimes end up being shot off a castle with a ballista, but those are the risks the Chaos Engine takes.
Wade has had characters fly into The God Quarry, fly into the distant future, confront the avatar of an Anti-God and died several times. It hit the point where he realised character death would negatively impact the whole group in Band of Blades so he armoured his first rookie up to a massive level. This didn’t stop Wade being Wade, so the character still charged a scrum of the undead, played with explosives and is somehow still alive.
My RPG community nights have Rhys, who at times talks like I’m frustrated that he’s the Chaos Engine, the most likely to start a cult or lose a hand in a Blades in the Dark standoff. The thing is, he’s pushing the story forwards and as long as that happens then the Chaos Engine’s a great part of a group.