H.P. Lovecraft's R.U. Pickman
I'm thinking of going comic-con next year as Richard Upton Pickman. I love that artsy little creep.
My idea would be to wear a dark, but (hopefully)threadbare suit appropriate to the 20's era. I would wear false fangs and eyeliner to suggest a less sane individual while hinting at his heritage. I would carry around a palette and brush, and have an easel strapped to my back with a fan rendition(from deviantart probably, but only with the artist's permission) of one of his works in the making.