There are only four classes, Mage, Cleric, Thief, and Warrior, but there is a world of possibilities. Many character types are hybrids of two or more classes, others are straight one class. Here are detailed some of the more specific character types. Gender specific pronouns do not indicate which sex is better at the type in question. Also note that these are not intended for extrememly high level players, as they do not require specialization:
By far the most widely known character type, The Warrior Tank is pure stopping power. He is capable of taking tons of damage due to his extremely low armor class. He trained his constitution early, meaning he's got tons of hitpoints, great for taking punishment. He doesn't have a lot of damage dealing capability, which is why he's mostly only functional when in a group of adventurers. The Magic Tank is common as well, having high Mage and Cleric Levels. This allows them a wide range of defensive spells, and the ability to heal themselves. They achieve a low armor class with equipment that has been enchanted. To be valuable to a group The Tank must be familiar with the rescue skill.
A Warrior/Thief Class, the hitter is capable of dishing out lots of damage. His hitroll/damroll is high, but because of this his, armor class suffers severely. His attacks per round is usually high, allowing him to get hits in while a Tank takes the damage. To be a hitter you must have a high dexterity and strength. A few supplementary skills such as kick, bash and disarm could be useful. A Hitter who knows cure spells or blasting spells is even more of a valuable asset. Again, this character type is not much good alone, but when coupled with a tank and a few other Hitters, he becomes a lethal tool.
A high level mage, The Blaster dishes out MONSTER damage. She's usually outfitted with cast level equipment, making her spells much more potent. She has trained her intelligence at an early level, to allow her a large amount of mana. She must be familiar with all offensive spells, so that she may be able to deal more effectively with different types of enemies. For example: Ball lightning is an electric spell, if a mob is resistant to electricity, then she can switch to demonfire (a fire spell). If that doesn't work cone of cold will freeze the monster. Area effect spells aren't very smart, because they can lead to mobs attacking the vulnerable mage.
The Healer is a primary cleric who is adept in all the major healing and protective spells. Blessing, Armor, Sanctuary...and groupcasting is a very important skill to have. Healer's keep the tank alive, as well as heal people inbetween runs who got hurt.
Named for his primary class, the Thief does not care much for groups. He's a well balanced character, knowing a few spells, has a decent hitting ability, and a low armor class. He doesn't truly shine however, till he sees something he wants. The Thief has a high dexterity and is good at parry and dodge. These allow him to fend off a monster till he can do what he wants to it. He is often very adept at steal and disarm, allowing him to take gold, weapons, equipment and keys from mobs without having to kill him. Do not be fooled though, a Thief with a high damroll can horribly wound someone with a backstab.
A rather uncommon class, in fact I only know of one or two. This mage has a WIDE range of spells. He should have a high amount of mana, but not as much as say...a Blaster or other straght mages. He doesn't have much mana because he has spent most of his practices on spells. Cast Level equipment is optional, because the spells it casts are not that complex, vital or mission-dependent. It makes a good leader because it does not get into the fighting, and can watch more closely the whole teams condition. It's called the "Function Mage" because it is a Mage (secondary cleric) who is adept at all the little spells a group requires. This includes but is not limited to: Fly, Water Breathing, Invisibility, Infravision, Detect Invisibility, Refresh, Famine, Noxious Cloud, Bless, Sanctuary, Heal, Armor, Summon, Locate Object, and Animate Dead. These spells are what make the world go around. What happens when in a group doing a corpse retrieval and none of the Level 30 Mage in their +10 Cast Level gear know animate dead or can carry the stuff? Call the Function Mage! What happens when you need someone to sit outside a room and summon the plebes who recall or die back? The Function Mage!
Yes, you might not know this but you can design a character with Player Killing in mind. He's a primary mage, usually secondary thief or warrior, followed by cleric. He doesn't know "swimming", he doesn't know "locate object". He's pure, hatred-breathing, blood-letting mayhem. His skills include bash and trip to throw spellcasting players to the ground, disarm to take his opponents weapon. Steal to take their gold BEFORE they die, so no one else get's your kill's gold. Famine, Feeble Mind, Noxious Cloud, and Blindness severely hamper your opponents fighting ability. The Fear spell will knock your enemy out of a safe room and into your arms. Backstab and Sneak are good. Summon is important, for cleaning those hard to reach places. Charm is great when pulled off. It almost guarentees victory (remove all?) His equipment is a solid mix of hitroll, damroll and armor class. He might also have a cast level set handy to switch in and out of. A high constitution is good so he can regenerate hit points fast and get back into the fray. You might think that your normal player can be an effective playerkiller, and maybe it can. However, if you want to make sure you can fit every skill and spell into a character, and not ruin your main character with a PPK flag, whip up a character of this type.
The ultimate in balance, The Solo Player is for those who aren't exactly what we'd call sociable. He's got a decent hitroll, damroll, armor class, hit points, mana, spells, skills etc... He's the way he is to avoid having to take time to adapt to his situation. He's usually rather experienced, and knows what he's doing. He avoids groups because he doesn't do enough damage to be an asset, and doesn't have low enough armor class to tank, and his spells are nothing spectacular. His only reason for existence is running experience and exploring. Solo's are BIG on exploring.