Oh this is an AWESOME thread, thanks everyone for the compiling.
Not to derail the list of mostly characters as opposed to "characters," I think besides the die-hard commitment to fascinating strangeness that is wadded into the shape of honorary* super-caller Spike, my all-time favorite "Is-He-Real" weirdo is Clark of Venison Stew.
I tried to listen to his podcast but without the counterweight of Tom giving it the context of reason and justice, it's just auditory holocaust footage.
*No, come on, admit it.