Defense-oriented fighters with magic, too

The knight is a class highly effective in physical combat. They have many skills associated with defensive fighting and get specialized skills based on what weapons they use. Knights are especially adept with shields, and they have an assortment of magic they can use to aid their fighting abilities. At high levels, knights can use the runic ability, allowing them to absorb magic attacks.
Purely physical, and can use combat styles

The warrior is a class specialized for maximizing physical damage output. Warriors get various in-combat abilities to increase their damage output, including the powerful suplex abilitiy that can actually throw an enemy into an adjacent area. Warriors get 'style' skills that grant them bonus stats and extra attacks in combat.
Comes armed with sneaky tricks

The thief is a class adept at sneak attacks and avoiding the enemy. Thieves can use their backstab ability to inflict extremely heavy damage on an enemy, and they can move stealthily through areas. Thieves can pick locks, haggle with shopkeepers, steal items, and do other generally underhanded things to assist them.
Thieves can choose one weapon type in which to be proficient, however they also automatically come with skill in short piercing (daggers). Thieves are the only class which can Scan into unlit rooms.
Magical artillery, possibly in a pointy hat

The wizard is a class which can cast offensive magic proficiently. Wizards get an array of spells to damage their enemies with. Wizards can charge spells to increase their damage, and they can summon elementals at higher levels.
Wizards also get certain spells specialized for what innate they have chosen.
Uses magic for defense and healing

The priest is a class which heals and defends using magic. Priests get spells with which they can restore health, and they can also cure status ailments. Priests can cast various stat-increasing spells on their allies. Priests can use elemental saber spells to empower weapons. Eventually priests receieve the Nayru's Love spell, which halves the damage received by the caster.
Priests can use the 'sacrifice' command on piles of money to recover their Mana.
Uses magic fueled by the earth

The geomancer is a class which draws upon the power of the earth. The effects of geomancer spells vary based on where the geomancer is fighting and what the weather is like. Geomancers can cast overgrowth to create favorable conditions for their other spells, and they can also control the weather. Geomancers can blend into natural surroundings with camouflague, and they can call gradually damage an opponent with their sandstorm and flurry spells.
Relies on minions to do dirty work

The summoner is a class which uses monsters to fight for the character. Summoners can charm enemies, creating followers to fight for them. They can cast spells to conjure creatures to assist them, and they can even cause their pets to explode with the Detonate spell. Summoners get skills as they level up to allow them to control increasing numbers of minions.