Original Touhou character made up on the spot by Toby Fox on his Tumblr blog, in the piece 'improvised touhou music with annoying commentary'.
As a result of her not having any art attached to her, only music, many artists have taken a stab at making a depiction of her. In the West, Mary Cagle's version of her (post #4789490) has become the most recognizable design due to its use in YouTube videos reuploading the musical piece. Similarly, in Japanese circles, as a result of a Niconico reupload of the musical piece using it, Khylimei's version of her (found here) has become her most recognizable design there.