I went to a small Halloween party with some friends last week - among the costumes were a monk, a witch, a vampire, and a gorilla. It got me thinking about those 4 as core classes in an RPG setting - an alternative to the classic fighter, magic-user, cleric (and rogue/thief).
What would that class selection say from a world building perspective? There's a religious order, but they're not the armor and mace type. There's also magic, but how are witches differentiated from magic-users? Are they a women only group, in contrast to a male only monkhood? Is it magical movement based in the countryside, as opposed to a city-based magic school? Is it focused on an oral spellcasting tradition rather than spellbooks and study? Gorillas - I guess they're sentient. Do these gorillas wear armor and have their own civilization or are they unarmored, beefy brawlers, barely one step above their wild cousins? Is the setting near a tropical jungle - a gorilla's natural habitat? What role do vampires play into this group? Are they the sneaky rogue type, blending into shadows? Are they spellcaster-fighter hybrids? I like this group - it's evocative; it says something about the world when these are your only options to be an adventurer.
