WRONG! I have played a wide variety of characters and personalities in d20 System. From a machinist Halfling to a Necromancer/Assassin, and as a DM I have create a wide variety of NPCs such as Dedric (a rogue/noble who caused strife through key assassinations), Visceris (a half god and exiled Seldarine who destroyed his homeworld), Kevlone (a vampire centaur and former druid, he's my favorite), Tippi (a halfling rogue gone ghoul who caused the party no end of trouble), and Nemesi (A dark fey, a Sith, from Ravenloft) whose primary weapon was an obsidian gythka.
You can make as varied as characters that your imagination can take you with d20.