I've been trying to put a list of the most common playstyles there are for MMO gamers and this is what I have come up with so far.

• Collector - This is the person who tries to collect all of something; whether it is all the "rare" pets in a game, rare suits of armor, etc. If it can be put on a checklist, they want it.
• Completionist - This is the person that has to do it all even if it doesn't really benefit them anymore; such as finishing "green” quests or doing a dungeon crawl just because they have never visited that area even if it won’t obtain them any tangible benefits.
• Crafter - This is the person who wants to create things more than anything else.
• Explorer - This is the person who wants to see the world; every little nook and cranny.
• Ganker - Not a PvPer but someone who likes to kill other players when there is almost no chance for the ganker to lose.
• Helper – This is the person who is always online helping others finish their quests, getting them gear, even if it doesn't benefit them at all.
• Hunter – This is the person who lives for the hunt; looking for a worthy target that can give them a challenge. Unlike the PvPer, a Hunter will hunt down and purse their opponent, waiting for the right moment to ambush or strike.
• Leader – This is the person who is always organizing others; whether it is groups, raids, or entire guilds.
• Loremaster - Unlike a roleplayer, a loremaster does not "get into character" often in game; instead they just love to learn the lore and backstory of the game.
• Master Looter – This is the person who desires virtual items and will run a dungeon crawl hundreds of times just to get that one particular item.
• Powergamer - This is the person who has to "win" the game in the fastest time possible. To them, fun is in winning and the path is just a means to an end.
• PvPer - PvPers live to compete; they continually want to test their skills against other living, breathing and most importantly, skilled opponents.
• Raider - This is the person who loves to do dungeon crawls.
• Reroller – This is the person that tries out a variety of different character types and has a hard time sticking to just one character.
• Roleplayer - This is the person who creates a persona within the game and truly tries to live like that individual while in the confines of the game.
• Socializer - This is the person who, more than anything, just wants to hang out with their friends and make new ones.
• Theorycraft – Tries to determine the “best” way to build a character.

Granted, some people would fit into multiple categories. If one appears to be missing, please let me know. Or if there is a better name (or terminology) for an existing one, let me know that too.

I don't fit any of your categories.  I'm an Adventurer.   I want to go on interesting and challenging quests, solve the riddle, save the damsel, protect the caravan, destroy the ring, kill the Lord of Darkness, save the land from evil.   I'm not a roleplayer in the sense that I'm pretending to be some other person while talking to other players, I want to be challenged by the adventure... to be drawn into the story, to be the hero of my own epic adventure.

Unfortunatly, I can't find an MMO game that offers this kind of challenge.  Woe is me, the sad Adventurer. 

I found this very interesting. I fall under a few catagories I would have to say.

I'd call myself a...

Collector / Completionist / Explorer / Leader / Master-Looter / PvPer / Raider / Theorycrafter

I want to see and do everything, maximize my character and their stats, own others in PvP and be the best in PvE.. But that game is only fun if shared w/ the company of friends / guildies.

Originally posted by AshenTemper

I've been trying to put a list of the most common playstyles there are for MMO gamers and this is what I have come up with so far.

• Collector - This is the person who tries to collect all of something; whether it is all the "rare" pets in a game, rare suits of armor, etc. If it can be put on a checklist, they want it. But have to add the collection have to have meaning, so not like getting out and collect 1000 boarlegs just to have them  but...if i't fits me role i probebly will collect it
• Completionist - This is the person that has to do it all even if it doesn't really benefit them anymore; such as finishing "green” quests or doing a dungeon crawl just because they have never visited that area even if it won’t obtain them any tangible benefits. Benifith gamewise or benifith funwise, as for me fun is my drive to play which also is my benifith, so like your example fishing, i did that but not for the fish especialy but more for the fun i had doing that with a couple of friends or when we did fishing contest's way back pre-cu SWG time  few times even when i played WOW
• Crafter - This is the person who wants to create things more than anything else. If the game has the right type of feature's i would enjoy with crafting similair to pre-cu or even current SWG then i am the type of person that will craft from 0 till max but doing that not in asap mode but in all and everything able to craft mode, aswell experimenting with different resource's,schematics you name it...unfortunaly i have yet to find a similair experaince i had in SWG, tho i know of a few games that do come close the overall style of those games didn't appeal to me. But in each MMO i have played i always tried r have played the crafter type's.
• Explorer - This is the person who wants to see the world; every little nook and cranny. Yup that me aswell
• Helper – This is the person who is always online helping others finish their quests, getting them gear, even if it doesn't benefit them at all. Well.....i'm not always online and when online i'm not ONLY helping...but i do try and help out allot in many way's, may it be answering qeustions, help them find certain area's, or in many cases just help others in having fun in the game i'm having fun with.
• Hunter – This is the person who lives for the hunt; looking for a worthy target that can give them a challenge. Unlike the PvPer, a Hunter will hunt down and purse their opponent, waiting for the right moment to ambush or strike. This could be me aswell, all depence on the type of MMO i'm playing, some are decent to get immersed as a hunter, some are imo bit to weak to immerse myself into a role as hunter
• Leader – This is the person who is always organizing others; whether it is groups, raids, or entire guilds. I use to be a leader, not anymore...but i still enjoy organizing,setting up groups...no guildds anymore (time man...not enough of that for me)
• Loremaster - Unlike a roleplayer, a loremaster does not "get into character" often in game; instead they just love to learn the lore and backstory of the game. Can i mix this up with Roleplayer  as a roleplayer in some games the background story gets my involved with the game, where in other MMO's i might creat my own story/lore still feeling involved with the game but just different
• Reroller – This is the person that tries out a variety of different character types and has a hard time sticking to just one character. Hmmm, i do try many different characters, but i always have 1 main character so i have no hard time sticking to my main, when he made max lvl i pursuit one of my alts, and afcourse occasionaly during my mains lifecycle it will hop to one of my alts just to get another taste of play....might be why i never been bored in any game i have played.
• Roleplayer - This is the person who creates a persona within the game and truly tries to live like that individual while in the confines of the game. see Loremaster, but like to add, i do not roleplay 100%, it's more like 50/50, if the community is willing, if the game lends itself towards roleplaying.......
• Socializer - This is the person who, more than anything, just wants to hang out with their friends and make new ones. I sort of fit this description, but i do not log on to make new friends, i might meet them and hang out with them in gameplay, maybe a bar/catina, but i can't do that constantly as i want to be doing something that i can't do in rl so if i meet people that want to just stand there and do nothing i am not one of them..hehe
• to be missing, please let me know. Or if there is a better name (or terminology) for an existing one, let me know that too.

You missed one.

The Merchant: This person strives to make a name for him/her self by offering premium crafted goods and/or services. In addition, this person also develops a reputation for being one of the wealthiest characters on the server.

Every MMO I have played has had one of these guys.

SWG - A guy named Thompson started the South Coronet Mall, he made his fortune by renting out vendor space (there were over 100 unique vendors at it's peak). He was also one the best crafters on the server.

EQ2 - A guy named Woodknot had several master tradeskillers and sold the servers best items from his home. He was a true "platinum baron".

WoW - A guy named Eyes started "Eyes Brand" goods and services. He offers everything - for a price. He even has his own slogan, "have you seen Eyes today?"

The Merchant player type differs from the "crafter" category as many that fall into that category strive to make the best items for their own use or for guildies, not necessarily for fortune and fame.

I fall into the Merchant category, however, I have never reached the level of fame and fortune as the players listed above.

Completionist/Hunter/Explorer. I also prefer casual forms of pvp.

I'm a mix of everything I guess.... when I first start playing a game, I like to take my time, explore and build a personality for my char. I usually end up as the guild leader and I do like adventure. As I progress through the game, I often find myself studying skills and looking at the future possibilities.

Back in SWG (Pre-Cu) I had managed to make a pretty amazing template to fight with and my combat style consisted of over 20 guns on my toolbar lol...

I like to kill people but I also enjoy good PVE and RPing :)

So... a bit of everything.

Reroller is a pretty good description, I'm always in search of a character with an automatic "I-win" button, but have yet to find it.  

Other sub categories might include Explorer, Hunter & Completionist.

theorycraft, explorer, loremaster.

• Completionist 10% - Love the feeling when you've managed to complete something, however I usually don't let the attempt to complete everything overwhelm my playing experience.
• Explorer 10% - Same here, it floats in with Completitionist kind if since I simply love to see everything the game has to offer, I want to "complete my exploration of the world".
• Helper 20% - I usually end up helping people. I always play the kind guy and I can't be evil against anyone, so I usually end up helping them because doing anything else would be evil.
• PvPer 30% - A worthy challenge and the knowledge that you fight a real player makes me love this. If the PvP is balanced and worthwhile I usually spend more than 30% here.
• Reroller 15% - I usually end up having a huge number of different characters that all are around the middle level, however this has changed a bit lately, before this could go up to maybe 30%.
• Theorycrafter 25% - How can you not love to theorycraft? This is one of my bigger hobbies in games, which may be why I enjoy Guild Wars as much as I do.

leader and Theorycraft

I'd go for lazyass gamer, but that doen't seem to be an option

i'm the kind of MMo'er that tries to creat a perfect char, fails to do this because it's impossible and because he's lazy then starts hanging in the cities and making guilds talking people into joining it

anyone like me?

Leader / Loremaster / PvPer / Socializer / (somewhat) Roleplayer

What about:

Packrat - like collector except keeps all named loot, even when long past its usefulness.  This loot doe not have to be rare, just Named.

Explorer/Crafter/Completionist/Packrat/Helper

I believe I'm a mix of 20% Explorer, 50% Helper, and 30% Socializer.

I suppose I'd be a "Master Looter", but I don't fall under that definition.  I'm simply a treasure hunter, who likes variety in my dungeon crawls.  This is why master looter doesn't really apply to me, because I'm not searching one dungeon over and over for a particular item.  I clear all the dungeons for a variety of items so that I can find or trade for things I need, and so I can sell phat lootz to other players.  Unfortunately, world of warcraft completely destroyed my preferred playstyle with bind on pickup.

Theorycraft + a bit of an explorer

lol... I got random itches of playing different ways.... Usually fell one day for a week or some random time also.. then hop to another one for no reason....

Im a combination of several

Collector, Completionist, Explorer, Loremaster, Socializer,  and just a hint of a reroller.  And my friend says sometimes I've got that hint of leadership..but honestly i hate having bossy roles sometimes ...you just gotta go if everyone is running around like chickens with their heads cut off hehe.

Hunter, Ganker, PvPer, Explorer..

I'm that guy that comes out of left field when you're in the most out of the way location to kick your butt.