"Dragons" can be just about anything underneath the dragonesque imagery.

My setting that actually has "dragons"... they're not creatures of plain old flesh and blood, they're elemental entities in physical form, ranging from powerful spirit able to manifest in the physical world, to outright quasigod. "Kill" one, and all you probably get is a rapidly disassociating glomp of whatever the dragon was at heart -- and likely an irked spirit. A fire-breathing dragon can breathe fire because it is, at heart, "fire". You might get a mountain dragon, or a forest dragon, or a rain dragon... or a shadow dragon.

You don't want to get a shadow dragon.