I don't have a current RP stereotype so I'm going to grumble about an old one. My group and I have only switched to D and D in the last couple of years, since we were all really huffed off at WhiteWolf and their handling of the InGame Apocalypse, and even more huffed off by the REALLY HORRIBLE new system, which pretty much makes everything feeble and uninteresting, and emo. I'm sure the system has some redeeming qualities, but I didn't like anything I saw, especially the new, much more complicated looking dice system.
Seriously, the old one was beautiful and was one of the things I loved about that system. You only needed one kind of dice and the ability to count past one. D and D you practically need a flow chart.
That being said, we switched to Dungeons and Dragons, and I've been annoying my game mates to limp through leveling and various die rolls since.
One of the first games we decided to play involved a really really old module from the original days of D and D, updated a bit to go with the newer system. "Keep on the Border Lands". We've... well... pretty much entirely strayed from the original purpose which was 'hack and slash your way through the monster inhabited caves', and we've made truces with most of the monsters living there. But I digress.
One of the things we did was to play a 'flashback' game of characters that had gone before the ones in the 'current' game. Well... My husband was playing the same character but younger, but he was an elf.
Anyway, we also had a psionic, a wizard, and me. I decided to play a Barbarian. He was there to act as a 'diplomat' to the local town, who wanted to obtain more grazing land for their cattle from the Barbarians.
Anyway, from the get go, one of the players ((Who has since left the game)) Pretty much started announcing every so often how "Stupid" my character was, and rolling their eyes virtually every time he took an action, especially if he got annoyed at something, or dug in his heels over anything he thought would hurt his clan. The character was extremely defensive of the land belonging to his people, since he saw cities and towns spreading like a sickness, and could picture a day where there simply wouldn't be a span of land wide enough to support the life style in which he'd grown up, so the requests for more grazing land didn't go over too well with him, but apparently this was just 'Stupid Barbarian Rage'.
It got old incredibly fast, let me tell you, especially since he only actually used rage -once- and that was because he was going toe to toe with a minor freaking demon, and it seemed like it might be a good idea.
I know the stereotype of the Dumb Barbarian as well as any player, but as a fan of the ORIGINAL Conan, ((Frank Herbert wrote some surprisingly poetic stuff.)), I'd have appreciated that my character be treated through the lenz that he was my character, not because the other player didn't like Barbarians, or that my character was playing a significant role in how things turned out, instead of a pissy little wizard who's player got pissed off every time they were reminded that most spells past cantrips took time to cast, and that a lot of them took material components.
There are a whole lot of RP steriotypes, and let's face it, they're there because they're the easy bucket to dump a character into. The big dumb muscle, the theiving rogue... the fragile wizard... and many of these steriotypes are enforced by the pros and cons of the class, but they're not the be all end all.
Our psionic was actually pretty tactically smart and good in a bar fight, and our rogue later became a cleric. He also never really stole anything, but he did engineer a lot of really clever pranks, and yet people automatically still bucket other peoples characters the second they hear the class. That's one of the reasons I used to like Whitewolf better, because the skill buckets were ALL open. You could define your character entirely on what YOU decided their profession was.
I think GM's might consider taking a lesson from that, and encourage players to not reveal what their actual defined class is unless they really have to. The character is more important than the file folder they go into.